Hi @Dpichler, welcome.
- is it possible to record the video footage (on the ROV or on the Laptop)?
Yes.
- is it possible to record the screen from the QGrundControl out of the box - or do i need 3rd party software
QGC can do it for you.
- can i use the dive log files to add them to a recorded video (see point 1) as an overlay using DashWare or a similar tool (i used this to rc drone videos and so on)
It’s possible, but Blue Robotics does not currently have a recommended/supported solution. If you have done this with ArduPilot drones before, then the same method you have used will probably work with ArduSub. @etienne has recently released his own third party software package to do this.
- tether quick connect (must have for the future) - anyone build something affordable?
Try searching the forums.