Recommend me a capture card (UK)

I’ve decided to get into the wonderful world of music videos, but my technical knowledge is sadly lacking. The guides on will probably be enough for me to get DVD and FMV footage into an editable state, but I’m going to need a capture card for my other videogame footage. The problem is that I’m really not sure what I need, how much to spend, what features I should be looking for in a card, or even what questions I should be asking.