Excellent Question!
I actually asked my law professor this a while ago(of course, I changed the "tickling videos" part of the question to just copyrighted films).
Exchanging and lending *original copies* of videos for personal enjoyment is 100% legal---because there is no profit motive. However, the burden of proof is on the lender that the lendee did not make copies or that this activity was beyond the lender's control.
Copying originals and lending the copies is usually taken on a case-to-case basis, even if it is with no profit motive. A judge would decide, for example, whether your distribution (i.e., lending of videos) materially affects the profitability of the production companies. Therefore, even though you're not charging for these tapes or just exchanging them for similar videos, the production companies (e.g., MTP, RealTickling, etc.) may claim that they're essentially loosing customers with these trades taking place.
The same thing applies to selling; once these videos are yours, you're free to do whatever you want, but only with the ORIGINAL copy.
Selling your old video breaks no law, because you now have legal title and right to the video. However, copying these vids (like many people do on e-bay) IS illegal, and a violation of the Copyright Act of 1980.
There are plenty of other interesting facts, including alterations to videos and others. If you want more answers, let me know.
Latin_Boy
