Create a backup list of my favourite YouTube videos, extract audio

I am using youtube-dl utility almost daily. I have directory with by favourite YouTube videos and I want to create a backup of this list. Not the actual content but only the YouTube ID's

Here is the thinking steps to actually get to solution:
List all files in directory by showing only filename and file extension:

ls -1

Monster Winer - Kerwin Du Bois & Lil Rick - Marlon Alves Dance MAs-CX-dRfhbzpA.mp4
My Songs know What You Did In The Dark (Light Em Up) - Fall Out Boy - Marlon Alves Dance MAs-ulgtWbARfV4.mp4

grep only mp4 files which suposed to be a youtube content:

ls -1 | grep '\-.\{11\}\.mp4$'

Cut off the mp4 file extension:

ls -1 | grep '\-.\{11\}\.mp4$' | sed 's/\.mp4//g'

This will now show:

Monster Winer - Kerwin Du Bois & Lil Rick - Marlon Alves Dance MAs-CX-dRfhbzpA
My Songs know What You Did In The Dark (Light Em Up) - Fall Out Boy - Marlon Alves Dance MAs-ulgtWbARfV4

Reverse the content of characters:

ls -1 | grep '\-.\{11\}\.mp4$' | sed 's/\.mp4//g' | rev

This will show:

ApzbhfRd-XC-sAM ecnaD sevlA nolraM - kciR liL & sioB uD niwreK - reniW retsnoM
4VfRAbWtglu-sAM ecnaD sevlA nolraM - yoB tuO llaF - )pU mE thgiL( kraD ehT nI diD uoY tahW wonk sgnoS yM

Now I cut the first 11 characters:

ls -1 | grep '\-.\{11\}\.mp4$' | sed 's/\.mp4//g' | rev | cut -c 1-11

This will show:

ApzbhfRd-XC
4VfRAbWtglu

But I need to reverse back the line content:

ls -1 | grep '\-.\{11\}\.mp4$' | sed 's/\.mp4//g' | rev | cut -c 1-11 | rev

The output is:

CX-dRfhbzpA
ulgtWbARfV4

Now I can actually put ID's in file:

ls -1 | grep '\-.\{11\}\.mp4$' | sed 's/\.mp4//g' | rev | cut -c 1-11 | rev > ~/favourite.videos.list

To create backup just exactly for youtube-dl utility I use:

ls -1 | grep '\-.\{11\}\.mp4$' | sed 's/\.mp4//g' | rev | cut -c 1-11 | rev | sed 's/^/youtube /g' > ~/git/rpi-stretch/home/.config/youtube-dl/boost.list

If I want to send these video ID's in email it is a good thing to add full url:

ls -1 | grep '\-.\{11\}\.mp4$' | sed 's/\.mp4//g' | rev | cut -c 1-11 | rev | sed 's/^/https:\/\/www\.youtube\.com\/watch?v=/g'

The output is:

https://www.youtube.com/watch?v=CX-dRfhbzpA
https://www.youtube.com/watch?v=ulgtWbARfV4

Appendix:
If I want to extract only audio for those videos and put it on the phone then I use:

ls -1 | grep '\-.\{11\}\.mp4$' | sed 's/\.mp4//g' | rev | cut -c 1-11 | rev | sed 's/^/https:\/\/www\.youtube\.com\/watch?v=/g' | xargs youtube-dl -f140

redownload:

grep youtube files.log | sed 's/^youtube /https:\/\/www\.youtube\.com\/watch?v=/g' | xargs youtube-dl -f140

Another:

grep youtube files.log | sed 's/^youtube /https:\/\/www\.youtube\.com\/watch?v=/g' | xargs youtube-dl -i --config-location youtube-dl.conf