there is a genre of educational math video on youtube where the lecturer writes math with a marker on a glass windowpane between the camera and the lecturer, and in the editing process they mirror the video so that the handwriting is legible to the audience. i attached a picture for an example

one of the best parts of these videos are the innumerable people comments who are blown away by the lecturer who is writing everything "backwards" with perfect handwriting and it is always very funny to me