The first is the "Girls of Cumelot," which features various porn stars having sex with some guy in his house or apartment. The girls (actresses like Kitty Marie, Amee Donavan, Kody Coxxx, Riley Shy....) themselves usually seem pretty bored and the camera angles are generally lousy, but it certainly meets the non-professional looking aspect of your request.
Then there's the "Reganomics" series, which is slightly more interesting by virtue of the fact that most of the girls who appear in it look like they are worried about having their heads chopped off by the creepy looking male actor. The girls (mostly amateurs, but you will spot a few big names who appeared early in their careers) spend between 5-10 minutes being photographed, giving head and getting fucked by the guy under the pretense of "auditioning" for the "adult film industry." The large majority of the scenes do not feature a cumshot of any kind, and the creepy actor is hung like a garden gnome. On top of that, his place looks like a pig sty. That said, there's a little bit of entertainment value in watching him provide instruction to the girls ("make some noise," as if the vienna sausage hanging in between his legs and the 1970's junk yard motif of his bedroom is bringing them any actual pleasure). Many of the girls are suspicious (I remember a scene where Kate Gold stops the action and demands to be paid in advance) and a couple of girls flatly reject him, which is kind of funny to watch. Like I said, I don't know how legitimate it all is, but it definitely seems to meet your criteria.
Lisa Sparxxx has also shot some swingers-related material that has an amateur/homemade feel to it.
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