A couple of observations:
Sounds - Not good at all. The AWS should ring - not bing. No 'clicking' noise from the brake handle but wierd noise from the direction lever. Not quite sure what the funny sound is at 0:18 on the video.
Numbering - A bit all over the place - needs tidying up.
Liveries - The black half moon & black front gangways didn't exist on the blue/grey livery. The ends were fully yellow and the gangways where also yellow on the outside (although normally dirty) as can be seen here:
http://www.semgonline.com/gallery/class421_02.html.
I would also say the grey panel is a little to large - the lower blue should raise up higher to just below the windows (only a lttle though)
The NSE livery looks pretty good. Only things noticable are the cab side windows shouldn't be grey - they should be red. The coach numbers wouldn't have the letter S before them and the set numbers wouldn't be 73xx or 74xx - they would be 13xx, 17xx, 18xx or 19xx.
Buckeye - Should really be in the raised position - Very rare for a SR unit to run with the buckeye 'dropped'.
Initial thoughts are mixed - a few errors in there - not like the class 101 which was very good.
Regards
Steve