I was able to get things working. Unfortunately, I am now experiencing both the stuttering video as well as the occasional grey screen video freeze while audio continues playing issues. I believe Infuse is aware of these problems and has promised an update to help address them.
I used the same settings as you, however “secure shared disks” is set to “device password” which I believe is the default. I did not need to change it to “with accounts”. I also have “remember this password in my keychain” checked. Time Machine functionality is not affected.
The only change I made to the stock settings was under the “base station” tab where I activated the “back to my mac” function. I was prompted to add my Apple ID and password.
I made these changes, but I was still getting an error message in Infuse that claimed that the time capsule folder was “empty – nothing to see here”. I then realized that my external USB drive was not spinning and was still in sleep mode. I accessed the USB drive using the connect to network feature on my MacBook in order to spin it up. I tried connecting to it again through the Infuse app while the USB drive was spinning and thankfully it recognized the media in the main folder and I was able to add it as a favorite.
In conclusion, I’m not sure if the solution was to activate the “back to my mac” function in the airport utility, which was the only change I made, or if all I ever needed to do was to make sure the USB drive was actively spinning before I tried to link to it using Infuse. I suspect the latter.