Happy to help. I manage Twitter advertising for a number of brands, and serve as an agency digital marketing strategist/technologist.
The card part is pretty straight forward if you have the original video file and can host it on your server. I'll work with you to figure out traffic and load based on your budget.
Depending on your ad budget, you might also want to consider calling a rep at Twitter's customer service and asking about the video card beta. I'm beta testing native video ads for one of my clients and I love it. Unlike most cards, my client pays only for a video play. Super efficient and as easy as loading a video to YouTube.
I'd love to hear a little more about you plans. I'm happy to help either by getting you setup with your card (Ads access, and server access required.
To avoid delays, should you go the route of Twitter cards, you're definitely going to want to talk with your webmaster or hosting provider about getting a security certificate for HTTPS:// prior to starting your card work.
Here to help,
Marc