[Retroman]

The proof against it = It's never been caught or properly found.
We're more than capable of tracking it down these days =] MORE than capable.

If there was a creature of this sort to be found, we would have found it.
Common sense is the proof it doesn't exist, such as the mention of its hair/excrement not ever being found.

If the only argument anyone can present is "oh well you can't prove it doesn't exist, so it does! plus, look at these videos online!" then that is just plain stupid. Mainly because, to prove it doesn't exist I would have to show you the entire planet all at once without any traces of Bigfoot.

If someone hadn't started the rumours about Bigfoot, then nobody would have "filmed" it and you wouldn't even be aware of it. Hence, the only reason you believe in it is because of the media. Without that, the thought of Bigfoot would never have even entered your head.