I reckon a lot of them were taped over rather than all in a fire. Some may have been lost that way but many older programs across a range of genres were wiped across all stations in the late 70's and early to mid 80's sadly.
There was a fire, and they did tape over games and it was mainly because of the massive cost of video tape. The fire took out a lot of 16mm stock - highly flammable, because they used to archive the video footage on 16mm, which is the opposite of what a lot of us grew up logically thinking about making VHS tape copies of stuff. We also lost a lot of Australian history on top of the footy.
There is also a story I was told, that they took a whole heap of possibly fire damaged reels and tapes to a tip. It was more likely he helped load them into skips and the skip owners took them somewhere unknown.
If anyone knows where, there's probably an archaeological dig on offer that would reap a huge benefit in my opinion.
If you go to page two of this thread I've posted a long story of how I came across some 16mm cans of some very famous old Carlton games from the late 60s that I transferred to digital.:
One lunchtime I mentioned to a work colleague that I was heading into name a game to pick up a vid of a recent win. He came along for the ride. I had called ahead to name a game for the game I was after and that I’d pay in cash. In we went, Toorak road south yarra from memory, parked, went up the lift,no one there but my requested copy was sitting on the front desk, I left the money,took the vid , job done. Old work colleague walks into a neighbouring door, scoops up 10-20 vids and calmly strolls out.
No wonder they went bust.
Pity it's not around anymore. While you couldn't always get everything you wanted, even from the 90s onwards (no luck with Dunstall's 17 goal game against Richmond in '92), it was nice to know that it was there to call on if needed.