So while I was playing tracks, a notification popped up, saying 'watch this video for FREE COINS' or something like that. I clicked on it, but the video didn't load, so no coins. Later I went to the shop, and saw an option above the others, here it is: I clicked it, I watched the video, I got 10 coins. Perfect. However, when I exited the video, this ↑ option remained. It turns out I can get endless videos, and therefore endless amount of coin rewards. I have already got 6107 coins, as is seen in the pic, but only half an hour ago, I had 5987! Someone please fix this. Refreshing the page doesn't get rid of the option either.
