Terry Pinnell wrote:

I have an Excel worksheet with several hundred hyperlinks to videos I've
made. So it's tiresome to get this message every time I click one to
play it:

https://www.dropbox.com/s/utgmnyafff...ssage.jpg?dl=0

I found several web articles such as this that seemed promising but
didn't work. Probably incompatible with Win 10. None of the registry
hacks like that which I've tried so far have exorcised the message.

https://support.microsoft.com/en-gb/...007-office-pro

So I'm still looking, and have posted in the Excel forum too. It's
annoying that I can't be trusted to open files I created from scratch
myself!

Can anyone here suggest a solution please?

Just a guess but wondering if this has to do with:

Internet Options - Advanced - Security section (at the bottom)
"Allow active content to run in files on My Computer"

With Microsoft, you can never be sure they don't borrow security from
other components in their OS or their other programs.

Issues regarding the security mechanisms with MS Office should be
addressed in a newsgroup that discusses that software. There is the
Trust Center set of options in MS Office where you can decide on how to
handle some actions.

https://support.office.com/en-us/art...8-143336039bbe

While you see "D:\path\file" in the dialog, I suspect your
*hyperlinks* actually use the file:// or another URI protocol to point
to the file. While it may seem strange, allowing links to "web" source
might also mean to any URI resource, like file://.

The article above provides help on MS Office 2013, 2010, and 2007. You
never mentioned which version of Excel that you use.