The same containers are used to contain chemical agents.
There are a lot of unanswered questions and a lot of agents of propaganda attempting to obfuscate the situation even more. Everyone has their own agenda.
the one thing that seems indisputable is that chemical weapons were deployed.
If Donald Trump says the Syrian govt. did it, I believe him.
The one thing that is indisputable is that you posted a link to a months old (look at the dates of the early comments to your linked video) Islamist propaganda video. While you might not believe it, ISIS is not above doing a chemical poisoning or attack on their own people (or, better yet, on captured Christians/Yazidis) to make propaganda videos. They have done this in the past.