Can gravity be unreliable?

As a physicist I take a certain sense of certitude in such phenomena as gravity. So the question with gravity can be unreliable seems very threatening. As a result I feel compelled to share this image/video from the Scottish Isle of Mull in Scotland where gale force winds from Atlantic storm Henry caused two of the island’s waterfalls to flow up last week. This video was taken by a local and shared online.

What next?  Shades of Macbeth:

“I pull in resolution and begin
To doubt th’ equivocation of the fiend
That lies like truth. “Fear not, till Birnam wood
Do come to Dunsinane”; and now a wood
Comes toward Dunsinane.”