I've never seen an HDMI to Firewire converter -- they are
very different standards, so I don't see how that could work......
If you try and capture the video, using the RCA connections, then you still need to have some form of 'capturing' the analogue (composite) video signal that the 'yellow' connector sends. (The red and white are just audio).
Not sure how you would do that, on a laptop.....and even if you could, you would lose quality
You don't lose any quality at all, by going for the Firewire option, with a cheap firewire card installed onto a desktop (you must know someone with a desktop you could 'borrow' for a little while?).
Firewire cards are not expensive -see here
Amazon.co.uk: FireWire Port Cards for example --and as I mentioned before, the software
WinDV to capture the DV footage from the Firewire card is free.
I think it's the only way, unless someone else can suggest an alternative option for getting a Firewire port onto a laptop.......