The ELDT course, created by JJ Keller & Associates, contains videos where the audio is becoming less and less supported by browsers and devices.

The videos in the FMCSA Compliant Entry Level Driver Training Program are currently not compliant with Apple products, Chromebooks or newer Windows systems. According to Apple.com, the audio must be MPEG AAC, and the publisher's videos do not use AAC compression:

According to Google, Chromebooks no longer support MPEG codecs:

Work-around: Try the Edge browser or Install VLC Media Player