Dear Joseph, many thanks - this is very helpful. And sorry about more than Q in the posting - I am strict with my sts about this!
The reason I don't want sts to upload pics is because eventually it will consume a lot of space. Streaming them is a better option for me.
Your point about the HTML edittor had not occurred to me - I would like to disable the pic and vid elements of this if possible. On the other hand, they are needed to enable streaming. Oh dear.
So to answer your "teachers as well", this is something I would like to see in Permissions, i.e., which roles can upload ...
Thanks and now to the second question ...