It's been about 2 years since the videos on the steam page have been updated. It's probably time to add a new one to showcase all of the improvements the game has gone through over those two years. We've had 2 new maps, numerous new cars, new sounds and a ton of other minor improvements. Plus, the team has really improved at making videos (the video for the wentward looks so professional) and we've gotten some new tools to make video production easier (replay tool).
Honestly there isn't much improvement yet: i believe they will do one once the career mode gets released or if they get MP working.