There is no easy way to do that. The effort is too high. Some thoughts:
1. Syncronizing video -- flight log: You do not have the exact time point when video starts in relation to the time line in the flight logs. Time stamps in the flight log are related to boot time of the drone. You need to find the offset when video starts.
2. Timing of the snapshot: I do video snapshots by VLC. VLC takes the current date/time when the snapshot was taken to the file name. I could not found a time stamp related to start of the video or frame number or something like that in the snapshot. I don't know if other applications have the possibility to store that metadata somewhere.
There may be a possibilty to synchonize the time in video and flight log by video file creation date and flight log real time (MAV message SYSTEMTIME). But this needs deeper inverstigation...
Remains item 2.
It is difficult to know what your purpose for this is, but with the H520 you can get photos with this information by using DataPilot and doing a survey mission. The photos will also be in a higher resolution than extracting frame grabs from video.
All you have to do is request the video recording with the subtitles.
These subtitles will give real-time video, the position of the H520, the altitude (reference to sea level), the Yaw - the Pitch and Roll of the camera etc ...
The video file must be in MP4 and the subtitles are visible when watching the video with BS-Player for example (the Windows video player does not display them). The subtitles are encoded with the video and can be removed during editing.
Check the coordinates on the pictures and find my flights.
And In BS-Player, all you have to do is request an image capture on the video to have the image with the info on it (if the subtitles are activated). The capture can be done in display size or in original size.
I think not. Never heard about a subtitle feature for Typhoon H. The subtitles looks like the XMP data in the pictures from E90 cam. The snapshot has XMP data in the file but nothing from subtitles.