Solution for CS custom firmware is here:
http://forum.softpedia.com/topic/999318-himedia-q5q10-quad-core-android-442-tv-box/page__st__414#entry18495056
YouTube 1080p:
A. install OGYouTube from here and enable all quality.
(if black screen you forgot enable all quality)
B. Spoofing_Samsung_SM-T325 download from
https://www.mediafire.com/?504cb07bdh85x and update from menu.
(Don't to A+B well stack with adaptive streaming on 1440p)
Thank you very much to pcristi (cristianstoica CS)!!!
1080p with the regular Youtube app is working now.