Gary does have a lot of experience and knowledge, but he is no more expert than a lot of others on the forum. I do have different but similar RV experiences over 50 years where I did the vast majority of maintenance and repairs to my own RV as well as those of may friends and/or fellow campers. For that reason, I'll offer some thoughts and if you don't want my advice, you are free to ignore it.
The most positive thing that I'd say about the pictures and video is that if it comes from the seller, they sure didn't hide the poor condition of the upholstery or the awnings. The awnings are unusable and will need to be replaced before any use. The upholstery would be a must for my wife but perhaps you can live with that. The main awning will probably cost about $150 if you do the work yourself and at least twice that if you hire it done. Slides will cost similar to that. I suggest that you get estimates for both before you buy. On the tires,
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The red above is the week of manufacture and the yellow is the year, so your tires (if they are all the same age) were manufactured in the first week of 2012 so are now 12 years old and should be replaced. Manufacturers only support tires for a maximum of 10 years and most experienced RV owners replace them between 7 and 10 years of age. As to the other pictures, they look OK as far as the go but pictures really don't tell you much. I believe that you would be very foolish to buy this rig without a professional inspection that checks out every appliance, and structural area and the chassis, engine, and transmission.