I also have this problem, sometimes I get to 15-20 mins into the video and it stops, or normally the audio just stops playing.
This can be reproduced by skipping/seeking the video to that point. In fact, there is a delay in audio sometimes when seeking from the start. Its almost like the audio stops downloading at a certain point, and is slower to seek than the video.
Its definitely something to do with the new Youtube separating video and audio streams, but I don't know how I can fix the problem.
I am using MPC-HC 1.73 with SVPTube 1.13.
I don't mind reporting this to the MPC devs, but id like to know how I can explaining in terms they can understand, reproduce and will be willing to help, considering the problem only happens with a third party app.
Thanks