Veteran South Sydney coach John Lang says TV cameras in the change rooms of NRL teams are an invasion of privacy, but also a necessary evil.

Lang was commenting on the Nine Network's decision to air footage of Manly coach Des Hasler slamming a door at Parramatta Stadium so hard it came off its hinges.

"I think it's a fine line and I think it is a bit of an invasion of privacy to be perfectly honest," Lang told AAP on Thursday.

"But in promoting our game we've all got to be prepared to give and take a little bit."

Lang said if the footage came from outside the period coaches normally assumed they could be shown on TV, it had crossed the line.

"If you start dredging things like that out, it's a very good way of probably having a negative affect on coaches' cooperation," he said.

"If that didn't come out naturally and they've dredged that out, well Des is probably not going to be very keen to cooperate in future, is he?

"He'll give the absolute minimum cooperation then that's required."

Lang said he had no problem with the practice if it stayed within NRL guidelines.

"We're all feeding off the same table so I think as coaches we have to be able to bend what we'd really like," he said.

"Personally I'd rather have no cameras at all but I understand that fans like to have a look on the inside.

"Providing it's done in the right way I think we can accommodate it."

Manly have threatened to ban cameras from their dressing rooms following the incident.

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