Onboarding is not the same as highlighting different features.
Onboarding should involve the user, in best case the user finishes a task that represents what he will mainly be doing while using the app to get him started.
If your app is complex then onboarding is recommended, but keep it mind that the user should have the possibility to skip the onbarding at any time because many users just don't like to get forced to finish onboarding.
Regarding the video tutorials, if your onboarding is decent i don't think video tutorials are needed, at least i have never used an application where onboarding was good and i needed additional video tutorials just to use it. Keep in mind that people using mobile apps don't really want to be bothered by watching video tutorials just to be able to use the app, you have a lot of competition and the slightest annoyance will make users uninstall your app.