I believe it shouldn't be video card drivers because it doesn't make lags when you download it, mostly it could be CPU, start task manager and minimize it, then watch the vid and see how high is your CPU % going
![Cheesy :D](https://dota.eurobattle.net/la/forum/Smileys/efko/cheesy.gif)
And yea, try that "ccleaner" advice, it should lighten your browser a bit, after it cleans the cache etc.
![Smiley :)](https://dota.eurobattle.net/la/forum/Smileys/efko/smiley.gif)