Portability isn't a concern here. Realistically, an extremely small fraction of your users have unsupported browsers. Maybe some forums won't let you embed video, but if you're building a product site you have the freedom to use whatever you please.
Wouldn't it be nice if your marketing wasn't covered in artifacts? Every GIF on this page is full of artifacts. Would it be valuable for users to be able to pause and appreciate a feature they think is neat?
It's high time for GIFs to die. HTML5 video is a worthy replacement.