there are apps you can use(harry's lap timer) to do that over cell phone video, or you can edit in after with something like racerender if you have the raw video and the data to lay over it.
the other option that I use is called solostorm, but that does data as well and requires a gps dongle and either a dedicated tablet or giving up your phone during runs to collect the data.
I tend to geek out over the data more than using the video aspects of it, but the software does have the capabilities to run video with overlay as well.