This app is no longer maintaned. Instead you can try MyTikTokBackup https://github.com/tmk907/MyTikTokBackup
How to download your favorite videos or any profile videos.
TikTok app: Go to "Settings", "Privacy and safety" and change "Who can view your liked videos" to "Everyone".
Open your profile page in web browser https://www.tiktok.com/@yourprofile
Open developer tools (type Ctrl+Shift+I or choose "Inspect" from context menu)
Switch to "Network" tab.
On your profile page open list with liked videos and scroll through videos.
Download har file.
Launch TikTokDownloader, choose download folder and 'Download from har'.
You can close application at any time, next time you open it, only new videos will be downloaded.