[velma]

I think people can get defensive & then more cling on to the idea that what they're doing is fine if you're too direct as people do get their backs up when they feel attacked. I think the idea of approaching this by sending things like YouTube videos is a good idea. A "this is such a cool toy/set up/idea. I might see if I can make it work in my cage/that hamster looks like he's having a lot of fun" type messages might encourage your friend to want to watch the videos and hopefully she can make some adjustments.