Much has already been said that I agree with, but this is very fascinating for me nonetheless. I've never studied anything like this, so the am already learning a great deal! I never knew there was a "code." Maybe this explains some of the more risqué Tarzan movies that came out early! Very interesting.
1. Of course the clip shows a brighter side of life! It was the depression, other than The Grapes of Wrath, who hold want to focus on the realities of the day? A nice escape it wonderful. It really isn't so different from today. Those of us in middle-America fantasize about Broadway and Hollywood and dream of being able to go to shows at will and wear fine clothes for no apparent reason. It just isn't that way for most of us in our day to day lives. So I see how showing the "brighter side" became so popular, and really, kind of necessary.
2. Themes/Approaches - I imagine that other films of this era will also be a little cheeky, a little playful, a little "overdone." This help moves things along and keep it light-hearted and less like real life. Love is always a theme, and a battle for the fair maiden is going to continue - far past the depression era!
3. I imagine that the dressing room scene would have been far different before the code! If you consider what was shown and discussed in Broadway Melody, then you can imagine that we would have seen more of Held as she was changing clothes - at least would have seen her shoulders, maybe even her back and/or legs. Very little was actually shown, it was more implied. Also I imagine the men would have made it to the dressing room, not just their flowers, etc. Even her dance number would have probably been more open and may have even included men, or closer interaction with the audience.