There's a video called Tina's Tickling Terror where the girl starts crying at the end so they let her down and end the video, but this is out of print now. then there's the famous Nonconcent Tickle from Paradise Vision, and there was another one by Real Tickling, but I believe it's out of print, too.
One video, Silk Stocking Tickler, is one of the worst. The ticklee is so ticklish, too ticklish, that they start fake tickling her in the video. Mistress Sandra Locke did a video with a slave, Mischi, who consented to the video, but was so ticklish that she would beg to be spanked to make it stop (don't know the title, might want to check her site). There's an ancient (mid 70s) film to video x-fer called "More Than She Bargained For" where the ticklee just gets tired of being tickled and keeps demanding for it to stop.
