Need Some Advice

Oke so im a bit stuck here on something right now im using dxtory to record what im going to stream(for reasons of uploading to youtube in higher quality) but im also using 2 audio channels

Now when using dxtory's codec even a few seconds is easily 400mb yet sony vegas can read it off the bat and compress down quite a lot but 30 minutes is still about a gig and thats a lot when you have a data cap to worry about in a household of 4 active internet users :/

There is the other codec xvid mpeg-4 but sony vegas cant directly read it yet would allow me to record 720p for 30 minutes to be around 500mb and still look great

Yet there is the problem the file itself has 2 separate audio channels my mic and the rest of my sound i could go for a 1 channel option but that would mean people would hear everything eg my breathing and such

So i was wondering does anyone know of a way to get files with that codec to work in vegas or any program that would allow both audio channels to be put in 1? as i know of a way but that involves converting it over several times and that does not help that much at all :/

honestly, what I'd recommend is skipping the whole recording to disk thing altogether.
what you might want to look in to is something like FF Split to get the best possible quality out of your stream, and then use Twitch's upload to YouTube feature.
If you need to edit for time, or add a title graphic, you can do all that right on YouTube now.
also, with FF Split, you can set a Push To Talk button, so you will only record your microphone when you push this button, but it will still record your game audio always.

edit: also, FF Split is free.

A program I've used over the years (and it's really popular among mic spammers) is Virtual Audio Cable (VAC). It lets you setup virtual audio cables. You can also have audio rerouted. So you can have the game output it's audio to a virtual cable. Also put your mic out to the virtual cable. Then have your recording program record the virtual cable. You can also have the cable output so whoever is listening can listen to both your game audio and microphone. It sounds complicated but it's super easy.

There's a free trial you can try to see if you like it. http://software.muzychenko.net/eng/vac.htm
Here's a link straight to the free trial download. http://software.muzychenko.net/trials/vac412.zip

lonesome i use vac atm to have it so that when i stream people hear what i say and what i hear due to me having a usb headset(wireless) as else i cant hear anything or i cant record anything but its also vac that is part of the problem as to why i have 2 sound sources to deal with and spiffy i tried to use ffsplit before but it can never get a stable upload speed even tho the program itself is a lot better then xsplit in a lot of ways

Oh and the reason as to why i want to upload it separately is because of my low upload speed so i cant really get anything above 854x480 without it lagging a lot as right now it does a tiny bit now and then where as i was going to record it directly as well(i have a 3tb hd setup for recording video's anyway) and then upload it in higher quality afterwards to youtube.
Its just the codec i wanted to use isnt recognized by sony vegas sadly enough(yet it is by youtube) so editing it is a bit hard and using a other codec makes it lag when recording it to hd due to the amount of data it has to write to it