In the Video settings, there will be an option for Trim to shorten the length of a video.
If the option for Video Trim is not populated in the video settings, there may be a permission missing for the user. Please speak to the admin of the Vidyard account and have the "Edit Style & Restriction" permission added.
Navigate to Groups and Users and select the group that is being managed. Select Options and then Edit Permissions. If Edit Player Style & Restrictions is off then turn this feature on to enable Trim.