Reduce music sounds using the DB sider on the layer, or just used the drag down or up on the layer of the music
Disable resampling, makes video quality better by removing frame ghosting, do this by going to properties of a layer and click on Disable resample.
Use Dxtory to record, you will get a extra layer for your microphone audio, so you can easily adjust your mic volume to the game volume, cause in some parts mic audio is hard to hear.
When you make the video in slow motion the audio is echoing, you can stop that by right clicking on the audio layer and checking Stretch to Fit.
If you need help PM me.
Overall good job.