I don't have access to the list of fish she gave at present on My hdd besides what was on her channel comments but seeing as that was months ago I'd rather just refer you and others here to a simple Google search for the search string fish for one gallon tanks...
We are all familiar with the image of a small fishbowl and a single fish inside. But can you actually keep fish in a one-gallon fish tank?...
www.aquascapeaddiction.com
I do care about the welfare of any animals in would buy which is why I have stated twice or more I'd only get ones for a one gallon tank. I don't see any unprofessional behaviour in O-Leary at all and she seems to be a well respected member of YouTube fish keeping circles. She has tanks she has run for years so she clearly looks like she knows how to keep fish.
We had a cat that died after an illness with heart problems, and another with a illness we didn't even know was wrong. Doesn't mean we didn't give it a great environment to live in with good food from Whiskers. We had a cat live to 20 and a dog die of old age too. Some animals just die early, and people do too.