welcome to the wonderful world of 'runnin' ball...' you should do some work before you get started casting your own:
get a copy of Dutch Schoultz' method (here)
http://www.blackpowderrifleaccuracy.com/
and go through it a few times. Then get your rifle 'dialed in,' and you'll probably have to purchase some different diameters of sized cast or swaged ball. don't worry- the investment will be worth it! ...
then, when you're sure you know which ball/patch/lube/charge combination works in your particular rifle, go ahead and get a mold and a melting pot and a dipper ...
by way of 'warning' ... wear good leather gloves, long pants and closed toes shoes when you cast. don't eat or drink anything when you cast (it interrupts your rhythm anyway). if it's hot and you sweat, wear a headscarf or a cap or something ... even a small drop of sweat dropped in the molten lead will cause a mini explosion which will splash lead all over ... you want to be out of town if that happens! be up wind of the whole process (the fumes can mess you up if you breathe enough of them), and of course, wash your hands thoroughly when you're done. don't let children in the area (another distraction, and lead is very bad for children) ... it's a good idea to be outside when you cast.
this sounds like a whole lot of nanny- state b.s., but once you set up casting for the first time, it will be part of the routine and you'll barely notice it (the video looks pretty good to me, by the way) ... I forgot- use a wood dowel, not a small hammer, to strike the sprue plate, and have something soft for the ball to fall onto when they come out of the mold.
what you spend on casting equipment will more than amortize in a few months of shooting; when last I did the arithmetic, it was about five hundred or a thousand rounds and then you've paid for the mold and the melter. you're going to fire more than that over the ownership of the rifle, so if you run your own ball, you're ahead of the game.
cast ball does not (in my experience) produce any better or worse product that swaged lead (this is what you get commercially from Hornady and the other major ball makers) ... your mileage may vary ... many shooters actually prefer cast lead as more consistent ... if it's that big a deal, you can weigh your balls and remelt the ones that are too light or too heavy.
if the purity of the lead is an issue to you, you can buy a Brindel hardness tester, but I use my thumbnail: if I can easily dent the surface, i'll call it soft enough.
happy casting!