Disability discrimination can occur when people with disability are treated less favourably than people without a disability.
Disability discrimination also occurs when people are treated less fairly because they are relatives, friends, carers, co-workers or associates of a person with disability.
Disability discrimination can be direct or indirect. Forgetting about captioning your videos is an example of indirect discrimination.
From a DDA perspective, it would be discriminatory to show any video in any online environment, within any built environment or in any public space without providing captions.
Captions are required when any video has moving pictures. This could include promotional videos at an exhibition or conference, a video shown in a medical centre waiting room, an educational video, or even a Microsoft PowerPoint presentation with audio or video shown in a workplace.
So, to avoid risk, when showing any videos or making them available online, please ensure you have closed captions available, or better still, just provide open captions in the video so everyone can follow along, whether sitting on a train, watching during a lunch break at work, or more importantly, for people with reduced hearing or for those who are deaf.