As mentionned by @pnuts, TakoutTakeout allows to download an archive of your Google's data.
- Select YouTube
- Precise playlists
- Choose the JsonJSON format
- Click 'Next'
Once your archive created, download and extract it. You can find a JsonJSON file Takeout/YouTube/playlists/_J_aime_.json
that lists all the names of the videos 'liked'.
With a simple Python script :
#!/usr/bin/python
# -*- coding: utf-8 -*-
import json
# Reading data back
with open('Takeout/YouTube/playlists/_J_aime_.json', 'r') as f:
data = json.load(f)
for video in data:
print video["snippet"]["title"]