Can't replicate with Dxtory Stable (2.0.122)
Can't replicate this with Fraps or MSI Afterburner's in-built screen capture tool.
Needs further testing.
Would also like to note that, the horse that was mounted gets duplicated each time the user tries to reconnect.
I don't have this issue either.
When playing the game and the bug occurs, hold F3+C for at least 10 seconds. When you release the game will close and the Launcher will move to a new tab called "Crash Report"
That is the text required. If you can't select anything, there will be a button in the top left that says "Open report file". Which will open the bug report in a txt file.
Quick fix, does this still occur in version 1.6.4