Great video and great choice of music. One improvement I can think of is to
compress the audio instead of using 16-bit 32 kHz stereo PCM audio which alone took up 36 MB (i.e., 53%) of the 68.1 MB total file size.
Using
VirtualDub, you can compress the audio (while keeping the video component unchanged) and shrink the total file size down as follows:
192 kBit/s, 32 kHz, Stereo MP3 --> 39.0 MB total file size
160 kBit/s, 32 kHz, Stereo MP3 --> 37.8 MB total file size
128 kBit/s, 32 kHz, Stereo MP3 --> 36.7 MB total file size