I don't know what roman numerals get the rocks to open doors....
Have you checked out the relevant Wiki pages, quests, maps, videos, guides, walkthroughs & hidden gifts.
In certain scenarios it is much more easier to consult, study & follow the maps instead of the videos.
You can easily find the solutions to puzzles if you check out the walkthroughs & maps.....everything is clearly & concisely highlighted.... including hidden gifts.
The Wiki pages & this forum will become your best friends throughout your Diggys Adventure journey.
MAP - Siege Workshop
VIDEO - Siege Workshop
Mines, Maps & Videos