How do I prevent this from happening?

http://www.chess.com/livechess/game?id=731520841

Anytime I see my opponent move their bishop and knight, I know they're doing to try and skewer me by getting either my rook or queen with the bishop protecting the knight. Ther times they will use a queen and bishop to get my king out of the back end by constantly checking until I end up to the side of the board.

How do I avoid this or is there a YT video to show how to trample this move?

I haven't got time to go into details but basically by playing 4...h6 you're forcing him to do the move he wanted to do anyway, which means you need to work on identifying threats.

In that specific situation 3...Bc5 would be a safer move for you, 3...Nf6 was absolutely fine but needs to be followed up correctly. You might want to google 'Fried Liver Attack' for more details on the particular situation you found yourself in. However I would prioritise recognising basic threats over opening work at this stage.

Improve your board vision and don't be as careless.  Agree with James it's better to play 3...Bc5 following opening principles and focusing on identifying threats rather than openings.  However if you insist upon 3...Nf6 then study the Fried Liver since it's quite sharp.  A wrong move means you're losing. 

Yes, once you are in that position, 4...h6 is an entirely negative move.

4...d5! is the best move, which blocks the line from c4 to f7.  This allows Black to develop and set up some counter threats at the cost of perhaps being down a pawn for some time.  (Note that after 5.exd5 you do not want to recapture the pawn... Instead play 5...Na5, 5...Nd4, or 5...b5)

4...Bc5, ignoring the attack on f7, is also possible but it is considered a little sketchy and requires you to learn forced lines.  So until you've moved up the chain at Walmart I would suggest playing more conservative moves like 3...Bc5, 3...d6, or 3...Be7 where you don't have to deal with the immediate Ng5 attack.

commenter's are correct. either learn the fried liver as black or don't play Nf6. I usually go for a gambit after ...d5 ed b5?! but that's just me. do I know that bf1 is best after b5? yes, but does my opponent? usually not. It's a sharp game either way.

b5 might deserve a !? but certainly not a ?! unless theory's change a great deal since I've had a look. I didn't mention that line and also 5... Nd4 are all probably fine at least up to a very high level... but anyway all of those take study. If you play 3... Nf6 White can take you places where you do need to learn some theory just survive the opening. I actually feel the same is true of 3... Bc5 though maybe there's less there, but that 3... Be7 might be a lot harder for White to make sharp and I would recommend trying that out if you don't want to study openings yet. Maybe 3... d6 as also mentioned ealier is another option; I don't know anything about that move.