Videos:

How to have the best vibrato (4 easy steps) - Ray Chen

Ask Augustin: tips on vibrato - Augustin Hadelich

Violin vibrato made easy - Murphy Music Academy

Basic Vibrato - Kerson Leong

7 concert violinists teach vibrato - tonebase

How to produce and change vibrato: Maxim Vengerov - Classic FM

Tip vibrato in 1 minute - Murphy Music Academy

Vibrato - Nicola Benedetti

Elbow vs wrist vibrato comparison - vladimirdyo7301

Vibrato in 1 minute - Roblandes

Finding the right vibrato motion - tonebase

Ray Chen teaches wrist vibrato part 1 - Ray Chen

Ray Chen teaches arm/wrist vibrato part 2 - Ray Chen

Relaxing your hand for vibrato - glotone

Vibrato on the fourth finger - tonebase

Vibrato: beginning exercise - violinmasterclass

Vibrato on Wieniawski Legende - violinmasterclass

Vibrato on Wieniawski Concerto 2 - violinmasterclass

Wrist vibrato - Violinclass

Slow motion vibrato - Violin Lab Channel

Vibrato tips (part 1) - Daniel Kurganov

Vibrato on Mozart VC4 - violinmasterclass

Tip for vibrato (scroll support method) - Daniel Kurganov

Viola vibrato - Ronald Houston

Vibrato without shoulder rest - Murphy Music Academy

Vibrato fundamentals - Richard Amoroso

Vibrato examples - Alberto Reguera

Flexible, effortless vibrato - Nathan Cole

Interpretative-related questions:

-How fast?
-How wide?
-Intensity of the piece matches the type of vibrato?
-Fingering?
-Vibrato coming from the bow
-Inspiration from other instruments? 
-Stylistic approach to vibrato
-Evolution of vibrato from phrasing?