Is it possible to insert a video into the code for a website that will change into picture (e.g. slide show) for a person with less bandwidth

I want to insert a short clip (looping) onto a client's website but rather than it just not run for a person with less bandwidth (and/or on a mobile device) and make the page look messy, is it possible to implement a command that replaces the video with a preset series of picture's if the video size exceeds what that person's bandwidth can handle?