Hey - The code will break in the code wherever the limit is reached. So you will need to make your email less than 102/100kb to ensure it isn't clipped - which should be possible on most emails. If you can share your HTMl I'm sure the community will be able to give you some guidelines and advice to make it lighter.
@Freemium User - Checkout my blog post on all the fixes we use to make sure background images work on the most amount of clients: http://www.emaildesignreview.com/html-email-coding/html-bulletproof-background-images-in-email-3850/
Hey Victoria - not my work, but I grabbed the code because I was curious. Hulu embedded a video to work within an email. Code: https://codepen.io/emailjay/pen/pxoOXV
From previous experience, you can have the youtube video show up in gmail by linking the image - it works like a pop up. But I don't know of a way to have a youtube video play directly in an email.
Hope this helps,
The other thing I've noticed is when using Windows 10 - converting pixels (px) to points (pt) solves it for a few issues, also making sure to set the height in the outlook conditional comment css styling. To convert from pixels to points - multiply by 0.75
640*0.75 = 480pt