In your first video, you are correct, the machine is showing you the payout for three "Double" symbols. The credits window (and overflowing into the Winner Paid window) alternate between 1,000 and 10,000 -- the single coin and 3-coin payouts for that combination.
Your second video is showing you the payout for one of the RWB 7s combo with two "Double" symbols substituting for the 7s, and the 7 in the correct position (Red, White, or Blue on the proper reel) for a payout of 1,200 (one coin) or 3,600 (3-coin play).
Based on your first video, the third reel is displaying correctly. The first two reels are not. Also based on your videos, I agree that the reel strips appear to be on the correct reels, based on the limited information available by watching the videos.
Are you absolutely positive that the reel strips are aligned properly in the baskets -- that is, the notch on the strips matches up with the notch in the baskets (which can be located on the outside of the reel basket by running your finger along it and feeling for the bump on the side)?
Is it possible that you have slant top reels installed in the first two reel positions? Have you changed out the reels or reel baskets recently? Slant top reels are offset differently from upright reels, and would cause a situation similar to what you're experiencing, although from your first video one of the Double symbols is two below the payline, while the other is two above the payline, which isn't consistent.
If you have not changed out the reel assemblies or baskets since it was last working normally, I guess I'd be at the point of, "if all else fails, try the clear chip", but I've never heard of a game displaying the wrong symbols being fixed by running a clear. I strongly think you may have slant top reel baskets installed (with the other possibilities being the wrong SS (or ST) chip, or poor alignment of the reel strips within the baskets).
For kicks, although from the video it looks like they are, can you confirm that your reel strips have the following symbols in the order presented:
Line # 1 ~~ ~~ ~~
Line # 2 B7 B7 B7
Line # 3 ~~ ~~ ~~
Line # 4 RB RB RB
Line # 5 ~~ ~~ ~~
Line # 6 H7 H7 H7
Line # 7 ~~ ~~ ~~
Line # 8 BB BB BB
Line # 9 ~~ ~~ ~~
Line # 10 R7 R7 R7
Line # 11 ~~ ~~ ~~
Line # 12 HB HB HB
Line # 13 ~~ ~~ ~~
Line # 14 B7 B7 DS
Line # 15 ~~ ~~ ~~
Line # 16 DS RB RB
Line # 17 ~~ ~~ ~~
Line # 18 BB DS H7
Line # 19 ~~ ~~ ~~
Line # 20 H7 R7 BB
Line # 21 ~~ ~~ ~~
Line # 22 HB BB HB
R7 = Red 7
H7 = White 7
B7 = Blue 7
RB = Red Bar
HB = White Bars
BB = Blue Bars
DS = Double Symbol