Excuse my ignorant question: if I buy one of these is there any (vaguely legal) way I can use it to watch movies on long flights? edit: Never mind, I found out

Excuse my ignorant question: if I buy one of these is there any (vaguely legal) way I can use it to watch movies on long flights? edit: Never mind, I found out for myself. Rip from DVD to some wacky format, obtain app to play it. Perhaps I'll consider it, now I find myself flying (bleh) United with its severe lack of video.