Hi @Cicerale ! For an end user this is currently not possible via UI.
You can monitor the activity log and extract the informations who viewed a video, but there is only the viewed event without a view duration. This informations can be extracted from the Office 365 Security and Compliance Center under "Audit log search". Or you can use the API via PowerShell or ... to extract the informations.
And as I heared, statistics for end users are planed and coming, but when I do not know.