The Mid-Atlantic Geo-Image Collection (M.A.G.I.C.) is a massive online repository of explorable geologic imagery on landscape, outcrop, hand sample, thin section, and scanning electron micrograph scales. This YouTube channel hosts videos of thin sections rotating in plane and cross polarized light.
You can also find these videos, along with associated explorable images of the entire thin sections and related hand samples, at blogs.nvcc.edu/mineralogy.
The entire M.A.G.I.C. thin section collection can be viewed here: viewer.gigamacro.com/collections/iWJgiRPII2ZgbZu0
And the entire M.A.G.I.C. collection can be viewed here: viewer.gigamacro.com/collections/foIlWZTPiuDZmcbz