Having been on the receiving end of job applications I can say this:
Will putting in the extra hours into these assignments help me land a job?
Most likely: No, it won't.
Or maybe it will… but it is most likely wasted effort as the assignments have a totally different goal in mind than what a real product would do. If your diploma assignment is a useful product, meaning someone actually bought it or if it is even remotely successful open-source project, then you have something to show.
As an anecdotal evidence we had to actually reject one applicant because of the code he sent us was of a very simple school assignment that was not executable. I mean, if you have something to show up, at least make it do something.
Also, I was thinking of showcasing my programming skills with a video demonstration of my work. Do you think potential employers would respond well to this kind of visual resume?
As a general advice: don't.
Demonstrating your programming skills with video is a bit of a toughie since it can go both ways. I haven't seen any job applicant do this to demonstrate their programming skills, and what usually matters is the actual result you do.
Do this instead: Put the code that you've done in an open-source repository (such as github, bitbucket, etc.) as it will become a far more cost-effective for you to do than making a video of you fooling around with code. This is because any technical person that would review the code you've produced can assess your skills faster by reading the code in your repository than he would do while watching a video of you slowly writing the code. Note that anything that makes it faster for us to assess you, the better your application's chances are for not going into the round file cabinet (i.e. the trash can).
Jokingly; I guess if you actually make a video, the only one who would like it would be a over-the-shoulder hovering micro manager. I.e. some guy who wants to see you do every step. If there is any advice I could give you then this is a position I strongly advise you for not to get in.
OTOH, if you're into user interface design then creating a portfolio demonstrating the user interfaces you've built might be a good idea. But the videos better be mindblowingly good.