Feedback request and audio recording issue

Greetings! I recently streamed and recorded a playthrough of Portal 2's Peer Review DLC and I've been really eager to get feedback about it, but most avenues I've pursued took it to be a cheap shot at getting free views, which is understandable, I don't have all that many posts on Reddit, and asking people to retweet things just looks meh, so I figured I'd come to my home turf.

The main thing I'm concerned with is the audio quality of my own mic (the other person's mic has obvious issues). I've done my best to isolate the area I'm recording in, and I feel it sounds adequate when there's game music/ambiance in the background, but when monitoring I get a high-pitched buzz that seems to alter in pitch or intensity as I move around the mouse. Switching to a different USB port seems to resolve it, but it's not a problem with that USB port as I've just been swapping between two. Also I feel it sounds a bit flat... I've toyed with the idea of adding a slight amount of reverb in post

As far as hardware goes, I've got a Blue Yeti microphone connected via USB to my Gigabyte GA-Z68X-UD7.

The video itself is over here: http://www.youtube.com/watch?v=vIjyupsJCq0

Any feedback would be greatly appreciated