List of everyone and the names of the videos that they have watched

There are multiple methods available.

Using Excel:
1. Use Get & Transform (PowerQuery) to connect to Access DB and bring in schema as is. And perform transformation(s) required in query editor using GUI

2. Use Get & Transform (PowerQuery) to connect to Access DB but use query to bring in data as single flat table. However, since MS Access won't have Full Outer Join. You'll need another table (table which list all USER ID/Employee ID). Then using that as Left side of join. Use Left Outer Join.

There are other methods, but above 2 will likely be easiest for you.

No worries. It's the right place. You were just not clear on the constraints.

You could do it in Access. Doing the same as #2 with 3 table join using Left Outer Join to Employee Table. Just create the query in Access itself rather than in Power Query.
Or if you only need Employees on NeedToWatch table, do Left Outer Join on that.