Unless the "training videos" have a mission critical objective or problematic intellectual property / copyright challenge (repurposed vendor material like your earlier post, right to repair instructions, controversial end result- untraceable weapons) the exotic sharing app result juice is not nearly worth the troubled squeeze of user training and migration from the tried-and-true default sharing apps. Additionally, DropBox and OneDrive have multifactor identification for increased security. Transcoding the video files for increased compression can reduce their space requirements especially for screen recordings.
Anecdotally a key library partner started using a secure email app but subsequently reverted to the convenience of plain own Outlook attachments.