Well for actual hard sparring video clips there are not many out there.
Although recently a Wing Tsun club called Meihua who teach Wing Tsun applied a new scheme called Koong-Sao. Their website is: http://www.meihua.ee/en
It is quite good stuff although it just proves that when actually fighting you forget your actual movements and just box with them. For a clip: Video
This is only a taster if you go on the website at the top you can download the various video clips from the past years.
Also we have hosted a type of fight club where only very enthusiastic members can come and spar. Shh first rule of fight club don't talk about it. (oops) lol. It went very well I was so surprised as it really kicks your adrenaline in and you just forget techniques and just want to break your opponents neck. lol
I will upload one to youtube if my internet stops messing around.
Hope this helps.