Download the file with the button above
Rename the downloaded file to tb.bat
Start a youtube video
Open a command window in the downloaded directory and start with:
Unplug the laptop and wait. If the laptop goes to sleep (maybe youtube auto-pause) just wake and start the video playing again
If battery dies check the number of minutes with:
cmd> type tb.txt | find /c /v ""
If running is >100 and estimated is >120, record the estimated and stop the script with CTRL-C