AriFerrari you most likely are running a 5.x version of Safari. That version does not support the new flash video codecs properly and so you get glitchy video. You won’t get this on Youtube because they default to HTML5 video, we still use flash video for the desktop because it allows us to implement a reasonable amount of protection on user videos.
This is not a StudioVeena.Com Problem but instead an older browser issue.
There are two ways to fix this problem:
1) Use a new browser. Chrome or firefox properly support flash in a way that allows the video to work.
2) You can install OS X Mavericks from the App Store. This is a free upgrade and will get your computer up to the latest and greatest Apple operating system which contains the newest version of Safari.
Unfortunately the older version of OS X does not support the new version of Safari.