The experienced goalkeeper, who has since left the club, started his video channel when matches were played behind-closed-doors during the COVID-19 pandemic, however the 39-year-old continued to film them despite fans later being allowed back into matches.
Foster became a hit for his 'Cycling GK' YouTube channel, which was later followed by a 'Fozcast' podcast, which gave fans a glimpse into the life of a footballer.
Featuring interviews, funny moments and match highlights with footage filmed on a GoPro camera placed in the goal, the 39-year-old quickly attracted more than 1million subscribers on the video sharing platform.
However, during a season where the Hornets suffered relegation from the Premier League, Foster was asked to stop filming the videos by the club's sporting director, Cristiano Giaretta.
According to Duxbury, the goalkeeper promised that he would, but went back on his vow to produce more content.
It saw Foster fined by his club and apparently led to tension behind the scenes at Vicarage Road.
Speaking to the Watford Observer, Duxbury said: "There are many things that occur during a season that are politically sensitive and that we can't discuss with fans in the way I would like to.
"However, now the season is over, I'll say I think some of the videos were disappointing. Our sporting director, Cristiano Giaretta, met with Ben and asked him to stop. He promised he would, but he didn't. He was fined.
"We want a culture of excellence at Watford. Those videos were not that. I wanted to say publicly at the time that the videos were utterly wrong and we had fined the player and asked him to stop, but it just wasn't something I could do.
"In future, player contracts will have clauses in them to make it clear that sort of behaviour will not be permitted."
Duxbury also took exception to Roy Hodgson's decision not to go acknowledge the Watford supporters during the clash with Crystal Palace at Selhurst Park - the match that confirmed their relegation to the Championship.
"I did try, after that had happened, to allude in my programme notes to things that had happened which were beyond my belief," said Duxbury.
"Even if, as a person, your heart belongs at another club, you are still the coach of Watford. You've just finished a match which has seen you relegated and you ignore your own fans? No, you must go to your own fans and your own players. Words failed me.
"I've known Roy for many years and I was surprised and disappointed, but I suppose we must accept, if not truly understand, his explanation."