MH-9121 correctly seeking when editing the time in a media with two tracks

git-svn-id: http://opencast.jira.com/svn/MH/trunk@13648 e6edf6fb-f266-4316-afb4-e53d95876a76
MH-9146 controls not above the video when controls are not hidden

git-svn-id: http://opencast.jira.com/svn/MH/trunk@13649 e6edf6fb-f266-4316-afb4-e53d95876a76