By default, HeySummit will organise the sessions in your event in two ways.
All upcoming talks will be displayed under the Schedule tab on your event site and
All talks in the past, or that went live already, will be displayed under the Replays tab (unless this setting is disabled).
That being said, if you'd like your videos to be available the moment you publish your event or open it for registrations, you would have to schedule your talks on a past date so they'll be automatically available under your replays tab in the same place.
Go to Content > Talks in your event dashboard and create a new talk.
Under the Broadcast tab, select No Broadcast in the Advanced Settings, then click Next.
In the Replay tab, add your pre-recorded video details.
Complete the other talk settings to set the date and add any additional talk information.
Once done, click Preview and select Replay View to confirm that the recording is playing correctly.