Mobile phones are banned in prisons and it was unknown how the footage made its way online.
The footage quickly caused outrage with the Department of Corrections announcing it was conducting an investigation of the prison, which is run by UK firm Serco.
Mr Thomas contacted the Weekend Herald to express his disgust at the footage.
"They are just locked up and that's that. What about their wellbeing and safety? They are still human beings."
The fact fights were able to take place without being interrupted raised serious questions about the staff and the effectiveness of private prison companies, said Mr Thomas.
"The prison officers have got to look after their welfare to make sure they are being looked after properly and they have not done that.
"Having a private company to run the prisons, it's a cheap way of doing it but the inmates are suffering and therefore what a waste of time and what a waste of money."
Corrections Association president Beven Hanlon said prison staff were frequently attacked and also said any investigation must be independent.
"It can't be Corrections investigating themselves," he said.
Department of Corrections Northern Region Commissioner Jeanette Burns said the incident was being reviewed by the chief inspector and the findings will be passed to the Ombudsman as a further level of assurance.
"The Department is also reviewing its contractual options if the safety of prisoners is compromised or there is evidence that processes have not been followed in MECF."
She said internal investigations were trying to identify those involved and police charges could result from the cellphone use.
There will be more searches for contraband, including cellphones, as a result of the footage and "changes will be introduced to strengthen the structure around how prisoners are monitored during the periods they're out of their cells".
Corrections Minister Sam Lotu-Iiga was in transit overseas and unavailable for comment last night.
