[Dmitry Pavlovsky]

I signed up for this forum just so that I can provide my findings on this issue…
Right off the bat, let me just state that I’m using Sony Vegas 10 and not Adobe After Effects. BUT, I was having a similar issue and stumbled on this forum and saw all the frustration. Eventually I did locate a solution specifically for Sony Vegas. I will post it below and the link to the site. Don’t know much about Adobe After Effects, but maybe there are some similarities, and this may help:

With the Event Velocity envelope you have full control over the playback rate of your video and you can create great effects with it.

Right-click the first event and choose Insert/Remove Envelope | Velocity from the pop-up menu. A green line appears through the middle of the event. If you’re familiar with other envelope lines (like Volume or Composite Level), you’ll be familiar with the tools related to the velocity envelope too. If you don’t have experience with envelope tools in Vegas Pro software, don’t sweat it; they’re easy to learn.

Notice that the envelope line has a point at the beginning. Drag that point all the way to the top of the event. As you do, a ToolTip indicates the new velocity of the event. You also see that indentations begin to appear the faster you make the video. With the Event Velocity envelope, you can speed the video up 300%. (If you also change the event’s playback rate to 4.0, meaning 400%, you can set the actual playback rate to 1,200% which is the playback rate of four times faster sped up by the 300% increase in speed caused by the event velocity envelope.)

https://www.sonycreativesoftware.com/controlling_velocity_in_vegas_pro