ConPaste asks for the password every time when archiver asks for the password (and it happens on every archiver call - for all list and extract commands).
You should pass archive name with /h parameter to allow password caching (it is grayed on your video for all requests except last one), there is also /s option to make it enabled by default.
I usually add /s /h%AQ parameters to ConPaste in MultiArc commands.
I've released current version, some bugs have been fixed:
MultiArc 1.4.2.158:
+ ignoring spaces in packed/unpacked sizes in listings (e.g. for NanoZip)
* P modifier for %-variables now produces path with drive letter
* safe %F/%L expansion (support % characters in path; no command line length limit)
Since internally TC reads 7x files but does not write them I would use MultiArc for writing and TC for reading.
So you can add an option to MultiArc not to use an addon for reading and list but just for writing?
You can achieve this yourself: just do not associate 7z files with MultiArc in TC plugin settings, and select MultiArc plugin in Pack dialog and set 7z extension to target archive path.