Youtube videos played on IE used to be entirely cached in your windows temp-file folder & you could just copy em from there permanently.
I always kept offline vidoes to avoid wasting bandwitdth, but youtube wants you to reload again & again for each viewing so they'll get more adviews, and make it impossible to download. Whenever a downloading software/plugin comes along, they work around it. Anyone really beleive that this "dash" video segmenting idiocy is more efficient? they just want more adviews.
Remember long back when there were no ads in youtube? Youtube/Google invested a lot of time/money giving us "free" service for years until the masses became so dependent on it and couldn't let go after they added annoying video-ads, viedeo-ads in the middle of streaming videos ... etc, and who knows what else lies ahead. (maybe like tv, we'll get longer & more ads per video, & a paid version of ad-free "cable-youtube")
It would be great, and only if Google listened to the thousands of reviews, especially on Apple's App Store, about people asking them to let them choose video quality. At least when Apple used their own youtube app for iPhones, they let people choose standard or HQ quality. Ever since Google came in, I've only noticed two things happen to their newly bought Youtube app: ads, no option for video quality, and multi-tasking (new feature) that still doesn't let you turn off the screen and continue to play content!!!