With root and titanium backup, I just removed the youtube app that comes with stock.
After that I was able to reinstall youtoube from the playstore, choosing version 5.3
That version plays everything perfectly in HD.
Either install flash player and firefox, or dolphin browser and dolphin jetpack or install viral youtube app. Take a look here http://xdaforums.com/showthread.php?t=2579795
Thanks I will tray metod from "Point 3. Install the hacked flash player"
but like I wrote in first post, I got browser (boat) with flash player working
problem is that in "desktop" Youtube site on tablet some movies are playabe on all resolutions even 1080p an looking great just like on pc but still is many videos when you got message "no flash player instaled" is kind of bug or something, I don't know I will try that HAKED flash player app. maybe it will works with all videos on "desktop" YT
and about last YT app, its seems to be ok when i am on wifi, there is Hd maybe not full hd but is ok, before tested on tablet I've checked YT app on my nexus 4 but on HSDPA not wifi and when I am on my provider internet YT app plays videos in worst quality I think. and when switch to wifi is ok,.is not full HD but definitely HD
****UPDATE
haked flash player works like charm with Boat browser now all videos avalible on HD or fullHD in "desktop" YT site works. thats what I'am needed
and that haked flash player app should be "must have" app for tablet
The viral floating youtube app doesnt support 480p or 1080p because google splits the streams in to. 720p works flawless and it hasnt any great difference with 1080p.
I forgot to ask you what version of android you have, if you have 4.2 jelly bean then adobe's flash player should work with every browser that supports flash playback (like firefox or dolphin). If you re on 4.4 kitkat though you need the hacked flash player as google removed from 4.4 some critical files that the flash player needed.
Yes i have 4.4 CM11 , like I wroted up, the haked flash work like a charm, but I switch to Dolphin browser because Boat browser do not played all hd videos on YT like I was thinking, but Dolphin does. Overall I think that Boat is beter browser than dolphin, faster, lighter and smoother but is something for something, haked flash player support Dolphin and is somthing in that flash code because videos that I can't watch on Boat are smooth playable on Dolphin.
If some one got working youtube app with hd videos working please share,
I using Boat browser (and flash player on) but in "desktop mode" on YT site some videos works and some don't
mabe someone got mod hd YT app working on Gpad
Thanks