I'm sure there is some truth to it somewhere.
Will players be upset if they're told to watch footage of themselves being shit all the time? Yes. probably. This exact same "issue" already happened with LVG.
Last 10 years have shown that our players are dumber and lazier than most. Resistant to LVG, resistant to Mourinho, abused the trust Ole foolishly put in them and now clearly back to resistance mode with Rangnick. They'll find no sympathy from anyone for stuff like this.
If you want to know the players whinging about this to the media look for the ones who were playing under LVG and who are still here. Shaw, Martial, Lingard and Rashford.