I get asked a lot how I create my track videos.
Example:
Carrera vs. Boxster in Thunderhill clockwise (reverse) - YouTube
It's basically a combination of good GPS data acquisition a GoPro and using TrackVision (or RaceRenderer) to overlay the GPS data and the video
For the GPS data acquisition: Until now I was using a PocketPC based solution called "MaxQData". The company went bust a long time ago and my old PocketPC isn't very stabile anymore, so I was looking for alternatives.
Harry's Laptimer is nice but I missed the "predictive lap timing"
(Predictive laptiming gives you immediate feedback if you lost or gained time by - example - trying a different approach to a turn).
And finally I found that a fellow Porsche racer (he drives a 993 TT) apparently bough the rights to "MaxQData" ported it to the iPhone/iTouch and is now selling it for very little money under the name CMSLapTimer Pro in the iPhone app store.
You will need an external GPS module which will set you back by about $100, but then you will have more functionality than much more expensive standalone solutions.
CMSLapTimer Pro even allows you to record a video of your session which you can watch (with GPS data overlay) right after your session
CMS Lap Timer Pro video + data overlay - YouTube
So if you don't want to go the "super fancy" route using TrackVision or RaceRenderer to create your YouTube vidoes, you're all set.
Disclaimer: I am not affiliated with the company or developer, but we exchanged a few e-mails while troubleshooting one little bug (which he immediately fixed).