LSNBLDR-273; allow user to enter youtube URL with https


git-svn-id: https://source.sakaiproject.org/svn/lessonbuilder/trunk@127760 66ffb92e-73f9-0310-93c1-f5514f145a0a
LSNBLDR-270; prefix can be null


git-svn-id: https://source.sakaiproject.org/svn/lessonbuilder/trunk@127763 66ffb92e-73f9-0310-93c1-f5514f145a0a