Use the controls above for start, pause and volume. Let it download a bit before starting. If it stalls, press pause and wait for more to download.
For documentary videos, part of the fun is shooting them unscripted and on the fly, and then going through the footage to find the moments that "click" – the takes are sort of like video snapshots, and while I'm shooting I have to keep in mind how they will end up being edited. Hope you get as much enjoyment watching as I did creating them.