Strange, as I can't view any you tube links things on here, but yet have no trouble viewing any video type on the normal internet.
By that comment I am guessing your on a mobile device or tablet. Mmmm thinking about it, in your case, many tablets
Basically if your having issues viewing video's then you need to check your browser plugins allow the media you wish to view. So (do I dare say it) Adobe Flash video player plugin, unfortunately still very popular. Security risks and all that. Backdoors into ones system....not very nice

Most sites including youtube have or are in the process of transitioning over to html5 video player which is far safer and has standards. Unfortunately the forum is yet to support html5 embedded media. I cant view youtube links that are embedded on here either, because I refuse you use Flash. That is why I now also supply the direct link to youtube. Where you have the choice to stick with the now default HTML5 player or switch over to a Flash player, while youtube still offer it as an alternative option that is.
FYI I use the following Firefox Addon to control my Adobe Flash use.
FlashDisable
and then enable....
HTML5 Video Everywhere!
And then use the following to get rid of an a annoyance
Disable HTML5 Fullscreen Alert
Note some mobile devices and tablets do not support Adobe Flash so it wont. This is one of the reasons that the HTML5 player was introduced to standardize everything in a safe (safer) manner and make the media more accessible to all including the blind.
(:-})