Could I connect to 2 internet connections for downloading?

I don’t think so. I believe that the pathways don’t combine to increase either. You’d simply be downloading the same thing twice simultaneously, using both pathways at their individual speeds.

Too bad, that would have been awesome.

You can connect to two connections at once, but it won’t make a difference. I’ve had my wireless connected to a neighbor and my regular internet connection going at the same time—doesn’t make a difference.

If you have two ADSL (or other) connections with the same provider, you could bond them.

I’ve heard of it being done with ADSL2+ lines to maximise DL speed at close to 45mbps.

Here is an example of an ISP that offers the service in the UK.

I doubt you could get it to work with two independent lines though – you’d need access to the router config at the very least, and, I suspect, the ISPs would need to be involved.