I also had a bit of an issue with the Collector not moving straight away after you give him the 8 Gold Revolvers.
I walked away from the Collector & then approached him again.....I tried standing in different spots....eventually the Collector moved so I could access the key.
If it's still not working try completely shutting down your game & re-starting it.
In these types of scenarios it is much more easier to consult, study & follow the maps instead of the videos.
Have you checked out the relevant Wiki pages, quests, maps, videos, guides, walkthroughs & hidden gifts.
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.
VIDEO - PC
VIDEO - Mobile
Fan based websites
If none of these suggestions assist you.....I suggest that you contact Pixel support directly.
There are 3 different ways to contact PIXEL SUPPORT.
Remember to check your email spam/junk folder for replies
Do NOT send multiple Pixel support tickets in quick succession...otherwise their spambot might eat them
1️⃣ You can contact Pixel support directly through your game settings menu
2️⃣ You can also contact Pixel support directly through this link
Do NOT type in the white search box....scroll down to the categories written in BLUE.
3️⃣ You can also send an email to Pixel Support directly through this email address
If you contact Pixel Support directly via the email address below....you MUST include your player ID number....which can be found in your game settings menu