>>81746704 (OP)A single video usually has 4-6 separate scenes with different costumes, co-actors, settings and sex acts. Usually you just pick one and get off with that, or it's a continuing story, which makes things even better.
Also, most new JAV by bigger studios is still being released on DVD, so it's not like they can press a single 20 minute scene into a plastic disc and expect customers to pay the same price.
If you really think about it, 2 hours of back-to-back, professionally filmed scenes is pretty incredible when the western counterpart is selling you 2 minute smartphone clips they took in their own bathtub.