So has the labels like "Autonomous 1x" actually been a thing that Google has used before, or is it actually meant to be an "inside joke" jab at Tesla's previous videos that had small labels indicating the video was sped up and/or being human controlled?
Parts of the video are sped up. These are labeled "Autonomous 5x", etc. In some cases, it's not obvious, so it's useful to have the label.
And many popular robotics demos are either controlled by humans or scripted, so it's useful to have the "Autonomous" label as well to clear up confusion. For example, I know a lot of people who thought the recent Unitree G1 demos were autonomous.
Videos like these are so often sped up or Teleop, I don't think it's really a jab at anyone specifically, just making it clear this video is showing an Autonomous agent without any speedup.