USB Video Grabber ?

Hello,

I know this is probably not the right place for this post, but I could not decide the right section for it. The moderator may move it if necessary.

My question: did anybody try a "USB VIDEO GRABBER" like these ones ?

http://www.yatego.com/watercooling/p,47290eb8e36ce,46c2f0f4a44e51_1,msi-movie-vox-usb-video-grabber (German, Sorry!)

http://www.tinxi.de/product_info.php?products_id=432&ref=251 (German, Sorry!)

http://www.amazon.de/USB-2-0-Video-Grabber/dp/B000KY0U1U/ref=pd_sbs_ce_title_5

What do you mean about it?

Much thanks,

Zeno