Confirmed with SmugMug support:
- Videos are not auto-uploaded. You would have to manually select them and upload them. I submitted a feature request.
- iCloud Photo Library originals (full resolution) are indeed auto-uploaded to SmugMug if you have "Optimize Storage" enabled. I confirmed this myself with several examples.
I had previously had SM for many years, but cancelled a while back. So I created a new account to test this on Saturday. I have 51,780 photos in my iCloud Photo Library. I got the entire library uploaded in two days (I have 1gig fiber - although my iPhone on Wi-Fi really only uploads around 200-400 on average and who knows what SM maxs out to or limits us to).
Things I found:
1. The app recommends leaving it open during the auto-upload for best results. Presumably because iOS will time it out eventually. So I did this for the two days. The screen just dims after a bit, but does keep the app open.
2. My phone got pretty warm during the whole two days, which was expected.
3. Not all photos appears to have been uploaded. I only see 49,300 uploaded. All photos in my library should be either JPG, PNG or GIF.
4. After the upload was completed. I tested simply taking a new photo with the camera. I did not launch the SmugMug app, however it was opened just prior to taking the photo. The first photo I took got uploaded, however the version in SmugMug was low-res. I tested again with a few more photos and all of those uploaded in full-res. I asked support about this and they figured it was just a single anomaly.
5. The next day I tested taking a few more photos and this time opened up the app and kept it open for a while and non of the photos got uploaded to SM. So not sure what is happening now, but doesn't make me comfortable relying on this.
After this experience, I decided to test other apps that support camera auto-upload. I already have my full-res complete Apple Photo library on my Mac and it gets backed up to a Time Machine drive, ChronoSync drive daily, Carbon Copy Cloner drive daily, weekly, and monthly. Plus Backblaze and Google Photos (via Backup and Sync app). I still like the idea of yet another backup that will take all the photos and save them out of the library file organized (preferably) by year/month. I know I can pull all the photos out of the library package in the "Originals" and "Masters" folder. I figure if all goes to hell and I cannot recovery my library file, then I will have all my photos in some kind of organization.
1. Plex - I have my own Plex server that I use only for video, but I have played around with hosting my own photos there. I haven't played around with the camera upload in a while, so figured I'd give it a shot again. After some fiddling around to get it to finally start uploading, it did start and saw all 51k photos. I checked my Plex folder on the server and saw that it was saving most of the photos with a .plist file extension. I could open them fine on the computer and could even just rename them to .jpg. Apparently this is an ongoing issue: https://forums.plex.tv/t/plex-ios-camera-upload-uploading-bizarre-wrong-format/468236
So I decided to scrap this idea for now. I could certainly deal with this, but having all my saved photos with the wrong file extension doesn't sound great, even for a backup.
2. OneDrive - I have an Office 365 license with work, so I have 1TB of space. It does have a switch to enable uploading videos and it will organize everything in year/month folders. The photos screen in the app just sat at "Loading" for quite some time. Figure it would do that while it figured out my huge photo library. During that time, I did some more research and found that OneDrive camera upload will not auto-upload photos that are not on the device. So this was out.
3. Google Photos - I didn't try this one, but just wanted to mention it since it does offer camera auto-upload. Like I mentioned above, I use the Google Backup and Sync app on my Mac and point it at my Apple Photos Library and it auto-uploads everything to Google Photos. I have it set to "Original Quality" since I have 1TB of G Suite space. I've had this setup for a while now and it's worked alright. I did have to reinstall the app recently because it apparently just stopped uploading new photos. I like the Mac app setup better since then it is always uploading in the background and I don't have to worry about an iOS app killing battery usage or having to manually keep an app open.
4. Dropbox - I already have this setup on my wife's iPhone to automatically upload all the photos she takes and then I have a round-about way for this to get to my Mac and have them auto-import into my Apple Photos library. This is the only iOS app I am aware of that does the auto-uploading of photos via device location. This has been the most reliable way of getting photos to auto-upload. My wife never needs to open the Dropbox app on her iPhone. I always get the photos she takes.
I tested Dropbox on my phone to upload my entire library. The filenames do get renamed with the date taken, which is nice. However, all the photos just get thrown into a single Dropbox folder. I'm sure I could configure some way to have the photos auto-organize into year/month folders, but didn't go further. It also appeared to completely stop uploading whenever I would close the app.
So after all this, back to SmugMug, I'm not sure I will keep it as a source for another backup. I don't like that my videos are not also auto-uploaded and the reliability of an iOS-only backup is questionable. I already pay for Backblaze to backup my entire photo library and also have the Google Photos backup for kind of a disaster recovery. At least for offsite backups, I feel pretty safe, but I'm always looking for other ways to safeguard my photos. $50/year for unlimited photos-only backup is not bad at all though.