Public domain material isn't subject to any restrictions -- legally you can do anything you like with it. It would be respectful (but not required) to honor the intent of the material and not distort its meaning, and to credit the source.
Something is only properly called "public domain" if the copyright has expired, and there aren't any patents or trademarks applicable either. Many old books are now in the public domain, so it's legal to grab whole paragraphs from them without attribution.
It would still be plagiarism to claim that you wrote it yourself, though. (Not that you're ...
oTranscribe Web App
I've tried using oTranscribe with some success. It let's you input a local media file or a YouTube link. And it also works off-line. (!)
For a free web app I think it's quite decent:
Hotkey for timestamp insertion: CTRL+J
Clicking a timestamp jumps to that moment.
Hotkey for rewind: F1 (or CTRL+1)
Hotkey for fast-forward: F2 (or CTRL+...
Well, no need to worry about. Transcribing footage is something very easy now-these-days. What you have to make sure is that just write down all your audio in chronological order and he time codes of when each section begins and ends. Try to include punctuation and how phrases are expressed, so your are as close to the video as possible.
If you are seriously ...