Great, glad I can help.
JPP025 wrote the GitBook Guide which is updated regularly.
There is also a simple (slightly dated) PDF for getting started with Video Tools too.
Timing should be pretty good. If not, there is always the option of doing Heavy Import
from the video tools. (Which preserves the timestamps). Transcribe the new lesson and copy the timestamps from old lesson or replace the old lesson text with the transcribed text.