It was snaked and jetted without a camera. The place that jetted it was a new plumber, and I actually called them out to do the camera. He got there and checked everything out and wanted to snake it first to see what he found, and said due to the way things went he felt jetting it would do the job without the cost of the camera. This is after 3 previous places had all snaked it and said they 'hit dirt' and that there was a broken pipe under the house and that it needed to be dug up and fixed. This was when things were really brewing and water was backing up out of the sink and going everywhere and something had to be done, so after getting 3 opinions I had them dig it up to replace the broken pipe. Personally I don't think they found anything, but they say there was a plastic p-trap in a random spot on the floor that was broken. I don't believe them, or I think they struck it with their shovel and broke it themselves when they didn't find what they thought they would. The problem was back the next day and they came and snaked it again, and again the problem came back. That is when I called the last place to come and do a camera. I tried to fight the other guy about it but he refused to give a refund or do any further work...
Anyway, that was a little over a year ago, maybe even as much as a year and a half ago now. It has not caused a problem since, so I figured (hoped) the jetting did the trick. Now they have sent me the pictures of the bubbling toilet (that they said happened 4-6 months ago as well, but they didn't think anything of it after finding out the upstairs had taken a bubble bath), and they report that they have randomly heard the kitchen sink gurgle.
It was built in '59, but has basically all been remodeled since. The basement was finished at a later date as well, so I think some of the plumbing is newer. Most of the original was cast, and now there is a mix of cast, copper, and a little pex (mostly copper now I think). The lot is fairly flat in front with a slight slope in the back (so one side of the house the upstairs unit walks out to ground level, and the other end of the house the basement walks out to ground level, with a small/gradual slope between). There are several very large trees on the lot. The trees are all located at the perimeter of the lot (as far from the house as they can be), but they are large trees and even with that some of them are within maybe 10-15 feet of the house and I know roots could possibly travel that far. I have only owned the building for about 3 years. Did not have a problem the first year and a half, then things kind of exploded and within about 3 months we went from the first report of gurgling sink to things totally backing up.
Property is in Salt Lake area, so we experience all 4 seasons, but fairly mild winters since I have owned it.
I can't think of any other pertinent info, so hopefully that gives a good idea. I know this post (and now thread) is long, so if you are still with me I thank you for sticking with it and for all the helpful thoughts and ideas. Keep them coming if you have any more, but at this point I think it might be worth just doing the camera to get this over with and see exactly what is going on...