Don't fetch secrets.json file when the info is already avail from local storage

Test Plan:
- Make sure when info is avail in local storage it works fine.
- Make sure when info is not in local storage it works fine.
New minimized topic tree files with null mp4 videos rmeoved

Test Plan:
- Make sure a known null video no longer appears in topic tree when app
  is launched.
Code to remove and report on null mp4 url videos

Test Plan:
- Run script, spot check against untouched returned topic tree data