Alright, I see the video posted was for a Tab 2, not a 2S which is really quite different. So I'll try to explain this as best as I can
First:
The screen is held in place with some pretty strong adhesive so I found just pulling off the screen with a suction cup alone would not do it. I recommend having a friend help because believe me, it's hard to pull off.
What I did was use the iFixit iOpener tool, heated it up and placed it on two edges of the device that meet at a corner, I did this about 3-4 times (If you're in a pinch a heated cloth bag of rice would also work it just might take longer). After each try I used a suction cup to try to loosen the screen. Also what helps is if you use a spudger or some sort of spacing utensil to put a little space between the metal edge and the screen (I had to make space with a little force because I know the screen is almost perfectly sized so there is little free space). I had a friend help me and hold down the device while I pulled on the screen.
There is a ribbon cable connected on the top of the device so you need to be careful not to damage anything by ripping it out, so you'll only want to lift up the screen 3-4 inches on the end you pried it up, and then go around and loosen the rest of the edges before disconnecting the cable.
Once you do that you'll have to remove 19 screws (2 black 17 silver) to separate the batter compartment from the rest of the device.
Then you will remove 4 screws that hold the battery in place.
Then in one of the corners there will be a ribbon cable, you need to remove one side so you can slip the battery out, I found the one that is parallel to the longer side of the device easier.
Finally, you just need to detach the ribbon cable that connects the battery to the device, it should be directly in the middle on one of the sides that run parallel to the longer side of the device.
Now you can just remove the battery and replace it!
Just reply to this for any clarification that is needed.