This example shows how to embed audio and video files in LaTeX documents. (The videos and audios won't play in the Overleaf preview! Download the PDF and open in a suitable viewer, e.g. Acrobat Reader, to playback. But Acrobat is ending support for Flash by the end of 2020; so this may no longer work then.)
The oxmathproblems.cls was written by Keith A. Gillow. The latest version (1.3) was released on 12/5/2020. The class is based upon the standard exam class.
For more information please see the corresponding problem sheet class FAQ page