Haha yes, but it wasn't related to the cats.
The problems with the velcro were:
* The stitches that mated the velcro to the blackout material constituted little pinholes, so an additional layer was needed to patch those up.
* There's always a battle between the sticking force of the velcro and that of the tape that sticks the velcro to the window. The question is which one wins
* Velcro all around a sizeable piece of blackout material is pretty darn difficult to tear off - esp. without damaging either the tape (see above) or the curtain itself.
The net result was that during the years I used that room as a darkroom, the blackout curtains just remained in place. I could just as well have affixed them there permanently.
In my current darkroom I have removable rigid panels (which were surprisingly easy to make) which I just push into the window when needed. Far more convenient and effective!
It cost about $200 for a one window room, but this was a good use of the money: https://guardblinds.com. (I dont have any further financial relationship with this company)
I have had a darkroom since I was a kid. My last place up until about 12 years ago, I had a great space, only issue was a window faced west. Setting sun was an issue. I made a removable panel, careful fitment, black weather stripping, etc. I ended up leaving the panel in place full time and sealed everything with heavy black 3M tape.
Really hard to fight the sun. Nuclear fusion, line of sight, etc.