[gentoo-user] HTML5 player (YouTube) is a pain!...Alternatives?

Hi,

I get sick of this [CESNORED] HTML5 stuff coming from YouTube!
Most of the videos while playayaingnaying arereare stututterutering
liiklike helellell. 

I tested a lot of HTML5 addons to fix that problem and googled
around the world but nothing helps. The only thing I found is an
iconic sentence, which is true in this case also:
"You are not alone...!".

Is there any way to feed the stream from youtube direktly into
a not blown player like mpv/mplayer or such (I would prefer
not to load a complete gui (vlc) with any click again and again.)?

Thanks for any help in advance!
Cheers
Meino

PS: For the completeness:
I have tried to fix that problem by:
Restarting firefox
Disabling hardware acceleration
Disabling webgl
Checking, whether the YouTube-testpage shows "all ok" for HTML5 (it does)
Checking various about:config-setting for usefulness
De-/Installing various addons, which all promise the heaven on earth