(Yes, I know, late reply, even if I read the post in the day or the day after it was posted).
regarding skipping I'm Sorry - yes, that IS possible but very hard to pull off so I didn't do it.
You can also skip Three's a Crowd by the same bug, which I didn't do either (but I did skip in three's a company in the final level as that one is easier to do).
I think the space between the grav. line and the floor/ceiling is the same on I'm Sorry and Three's Company. I thought it was the same in Three's a Crowd, but I'm not sure...
As I wrote in the video info, the timer issue is due to a bug in VVVVVV. Its' timer shows a higher number than what has actually went. There's actually another topic in the forum describing this.
Where? The only bugs related to time that I know is the one that the Time Trial counter in 2.x. is slower than in 1.x. and real time, so that 5:00 real time ≈ 5:00 in 1.x. ≈ 5:06 in 2.x. Since it was faster than real time, it's not this bug. The another one, which I reported myself, is that the Time Trial counter starts at 0:00 when it's actually 0:01 (counting from the time Viridian started moving). It was 7 seconds fast, so that's not the one either. Where's that bug described?
That *is* the bug I'm talking about... You're doing something wrong
5:00 real time = 5:05 vvvvvv time, 12:45 real time = 12:58 vvvvvv time.
(keep in mind I didn't begin the run on 0:00 @ video)
Actually I think I started thinking wrong, then thought right, and you thought as wrong as I did at the 1st time. Let me explain:
When I said this, I was wrong:
(...) 5:00 real time ≈ 5:00 in 1.x. ≈ 5:06 in 2.x.
I should have said this:
5:00 2.x ≈ 5:06 real time and 5:00 1.x ≈ 5:00 real time.
This is correct. Yes, I did check the post that reported the bug.
Since it was faster than real time, it's not this bug.
^^^
This is correct (or I think it's correct), in fact, the below is correct too:
(...) the Time Trial counter in 2.x. is slower than in 1.x. and real time (...)
Also, I noticed it showed the total time (as 12:58) when the YouTube timer was at 12:51... 
If I remembered correctly when I said that (EDIT: I did), then it's faster than real time. IIRC, it started at 0:03 video time (assuming it starts at the beginning of the 1st cutscene) (EDIT: It's true), so it was actually in 12:48 (EDIT: or 12:42, if it stops as soon as the "Game Complete" text appears), making it even faster than it seems.
Where am I wrong? I'm going to check the video... EDIT (on quick edit): Checked, see other edits above.