Videos won't really help. You need someone to watch you and then advise you. Go along to a casting event and chat to some of the local guys.

Best start is to find a stance where you feel balanced. I find a long drop about half to 2/3 the length of my rod prior to casting helps to load the tip. Release point is always important too. The casting guys can help much more, but I find if you are releasing at about 40-45 degrees (that is where your rod tip ends up) then its there abouts.

The trick with learning to cast well is concentrate on the basics first. Balance, load the rod and get the feel of it before you start to attempt some power. For example, if you blast out with a ton of power but you are off balance and your release is early or late then your cast will suffer. Try just flicking the bait out using the tip, over and over, adding a little power each time. If you have ever tried fly fishing you'll know about the thumb on top of the rod. Try casting like that and you'll see it locks your wrist and forces you to load the tip.