I import 5 to 15 minutes movie.
Longer movies and some movies show error.
For a work around I found that you can manually copy the transcript directly from YouTube.
On a desktop browser, hen you are watching a video click the three little dots on the bottom right next to the thumbs up, thumbs down and save button.
Then click on “Open Transcript”. The transcript will open up on the right of the video.
To get rid of the time stamps next to each line of text look for the three dots at the top of the transcript and click “Toggle Time Stamps”
Then highlight and copy the text.
Now If I could just add the video into the lesson manually…
Yeah. The ability to embed videos manually would make this feature a little more bearable when there are issues like this.
As a workaround, is it possible for us to manually add Youtube videos into LingQ?
Thank you for posting this as I’m having trouble too!
I just want to point out that the ytmp3 cc site mentioned below as a workaround is considered to be a potentially unwanted program (PUP) and it may have ads and other pop-ups that download malware/adware. So if people use this site while waiting for the official LingQ fix, they should be very careful about clicking on any links or pop-ups. You can find more detail by googling “ytmp3 virus”
I agree that site seems off.
When I click download it takes me to a website and does not download the video. What am I doing wrong. 
This is working for me again (as of 4/9/2021 using chrome) so it looks like they fixed the problem. Yay!