A. If you have premium hosting with us then you can host your videos with us. We may put bandwidth or storage limits with overages in the future if we see a need to, but at the time of writing this we do not have any quantity limits.
A. It has to be embed code. With Premium hosting you can upload videos to the server, and then use FlowPlayer code to play it (or, we can do it for you).
A. The max file size is 4mb. For videos you can upload larger files using the upload video section (there is a link to it in the top right of the file manager).
