The OSD Subtitles utility combines OpenTX/Blackbox log files with Betaflight OSD elements and produces a subtitle file with OSD overlay similiar to the the Betaflight OSD. You can then play your flight video with subtitle OSD elements in a video player like VLC or import them into Youtube or some other web player. Not all OSD elements are currently supported and some may display differently from Betaflight.
Click on osd-subtitles to open the utility in the browser.
Read the how to for more information.