There is not any OOTB feature to automatically add caption to your
video, you need to add a parameter in DM component. Append the copied
URL of the video with the following syntax so you can associate it with
the copied URL to your caption file: &caption=,1Note the ,1 at the end of the caption URL path.
Immediately following the VTT filename extension in the path, you can
optionally enable or disable the closed caption button on the video
player bar by setting to 1 or 0, respectively. You need t...