Error: can't download

Why am I unable to download only this video

https://www.youtube.com/watch?v=ut_oLhMhJsY?

which is listed under the following playlists,
https://www.youtube.com/playlist?list=PLC71D7CFB6AF935E6
https://www.youtube.com/playlist?list=PLF360ED1082F6F2A5

Error: can't download.