Step 1
Go to YouTube watch later playlist and add the first video to a new playlist named the new watchlist. Make sure the ‘new watchlist’ is public so that you could download it with any software or do whatever you deem necessary.
Step 2
Now download an old version of Mozilla Firefox (55 or earlier) and old extension of iMacros (8.9.7 preferably).
Step 3
After completing the second step, open the main watchlist through the Firefox browser.
Step 4
Start the following macro in a loop. If your playlist has 20 videos to clear, loop the watchlist macro four times as it clears five videos for instance.
TAG POS=11 TYPE=BUTTON ATTR=ID:button
WAIT SECONDS=1
TAG POS=1 TYPE=PAPER-ITEM ATTR=TXT:Save<SP>to<SP>playlist
WAIT SECONDS=2
TAG POS=2 TYPE=YT-FORMATTED-STRING ATTR=ID:label
WAIT SECONDS=2
TAG POS=1 TYPE=DIV ATTR=ID:checkboxContainer
WAIT SECONDS=2
TAG POS=1 TYPE=BUTTON ATTR=ID:button&&CLASS:style-scope<SP>yt-icon-button&&ARIA-LABEL:Cancel
WAIT SECONDS=2
TAG POS=12 TYPE=BUTTON ATTR=ID:button
WAIT SECONDS=1
TAG POS=1 TYPE=PAPER-ITEM ATTR=TXT:Save<SP>to<SP>playlist
WAIT SECONDS=2
TAG POS=2 TYPE=YT-FORMATTED-STRING ATTR=ID:label
WAIT SECONDS=2
TAG POS=1 TYPE=DIV ATTR=ID:checkboxContainer
WAIT SECONDS=2
TAG POS=1 TYPE=BUTTON ATTR=ID:button&&CLASS:style-scope<SP>yt-icon-button&&ARIA-LABEL:Cancel
WAIT SECONDS=2
TAG POS=13 TYPE=BUTTON ATTR=ID:button
WAIT SECONDS=1
TAG POS=1 TYPE=PAPER-ITEM ATTR=TXT:Save<SP>to<SP>playlist
WAIT SECONDS=2
TAG POS=2 TYPE=YT-FORMATTED-STRING ATTR=ID:label
WAIT SECONDS=2
TAG POS=1 TYPE=DIV ATTR=ID:checkboxContainer
WAIT SECONDS=2
TAG POS=1 TYPE=BUTTON ATTR=ID:button&&CLASS:style-scope<SP>yt-icon-button&&ARIA-LABEL:Cancel
WAIT SECONDS=2
TAG POS=14 TYPE=BUTTON ATTR=ID:button
WAIT SECONDS=1
TAG POS=1 TYPE=PAPER-ITEM ATTR=TXT:Save<SP>to<SP>playlist
WAIT SECONDS=2
TAG POS=2 TYPE=YT-FORMATTED-STRING ATTR=ID:label
WAIT SECONDS=2
TAG POS=1 TYPE=DIV ATTR=ID:checkboxContainer
WAIT SECONDS=2
TAG POS=1 TYPE=BUTTON ATTR=ID:button&&CLASS:style-scope<SP>yt-icon-button&&ARIA-LABEL:Cancel
WAIT SECONDS=2
TAG POS=15 TYPE=BUTTON ATTR=ID:button
WAIT SECONDS=1
TAG POS=1 TYPE=PAPER-ITEM ATTR=TXT:Save<SP>to<SP>playlist
WAIT SECONDS=2
TAG POS=2 TYPE=YT-FORMATTED-STRING ATTR=ID:label
WAIT SECONDS=2
TAG POS=1 TYPE=DIV ATTR=ID:checkboxContainer
WAIT SECONDS=2
TAG POS=1 TYPE=BUTTON ATTR=ID:button&&CLASS:style-scope<SP>yt-icon-button&&ARIA-LABEL:Cancel
WAIT SECONDS=2
REFRESH