A) What client are you using? Any time you have a client issue, be sure to report the client, version of operating system, and version of Java.
B) Instead of a video, in windows you can click the text window, press ctrl+a to select all, and then ctrl+v to paste the text into your post. It'll make it easier to read the exception log. (All operating systems have similar mechanics to move information between applications.)
Just to note, there is an issue with the custom clients currently that needs loftar to resolve. See this post
viewtopic.php?f=49&t=40400&view=unread#p852771
Opinions expressed in this statement are the authors alone and in no way reflect on the game development values of the actual developers.