@arminunruh I've just sent you the log in credentials. Unfortunately the Wordpress recovery mode log in link is only active for 24 hours. After that you'd need a new one. Thanks so much in advance for your time and help with this! It's much appreciated.
Could it be that there is some issue with the coded used? I managed to upload a file using the mpeg4 codec instead of the h.264 (x264) codec and had no issues.. the file was 21 mb in size.