Here we expose some of the reasons why VAST should be your go-to format for video, rather than HTML or MRAID:

Ad Exchanges have integrated the VAST specifications template in their SDK, which supports quartile tracking (unlike HTML / MRAID Video). Therefore Videos will always be correctly reproduced.
VAST can tell you more about performance than HTML / MRAID, so you are going to get better performance metrics and reporting because the publishers pass back more parameters. With VAST Video format, you don’t need to use macros to track your events.
VAST generally has a higher success/completion rate than HTML / MRAID because of ease of use and creative certification.
Certification: You only need to be certified one time with VAST because bid requests and bid responses are so concrete. HTML/ MRAID video needs to be retested with each change in a creative because it is more complex and subject to breaking.
The VAST format has the potential to improve inventory quality, lowering latency and contributing to a better user experience.

How to upload videos?