Market research for an online video training content

I am keen to find out a niche market in-demand market for online based video training content. The content itself would be video recorded in a classroom, seminar or workshop setting with an experienced british speaker delivering a presentation. A typical training course would have up to 50 short videos split into 10 chapters.

I guess I am open to all sectors. For instance, it may be training for creative software (would have to be niche), health and safety, fitness and wellbeing, how to improve your career etc, how to increase your wealth etc. The list is endless.

Goal: To find out the most popular online video training subjects or searches on search engines. Analyse the data and come up with a target market.

Market: UK initially, but looking to go global. Private sector only.

I look forward to your response.