Wonderful tool for keeping your browsing efforts separated and fenced off from nosy Bots.

Seems like I had to do three things to make reopening in the right container "auto-magic";

Open a new tab in the "Amazon" container (long click on '+'). Past the URL into the new Amazon container tab.
Click the Multi-container symbol and select "Always open in Amazon"
Open a non-container tab and paste the URL, select "Remember my decision to always open in Amazon container"

After all 3 of these steps are done, the URL will always open in the selected container.

Once these 3 steps are done you're all set. However there are currently 2 things missing from this and other "container tools";

1. Easy Export/backup/restore/Import of container rules. It would be lovely if this capability were available in CSV and JSON formats. [Necessary for setup of multiple machines without Sync, and off-site storage of config(s)]

2. An easy way to Edit container rules beyond just delete and start over. This will allow quickly changing custom behavior(s). #1 might take this issue toward "feasible".

I put my own website (with multiple applications) in a container to keep nosy bots out of my site cookie jars.

Great idea, love having this feature. I'm tired of having everything I looked at on Amazon.com show up in my Facebook feed. This is a win for privacy and giving browser experience control back to the user. No other browser appears to have these tools, just Firefox.