Adding a Power Point slide deck to an uploaded video in Stream

As Loryan Strant  mentioned above, we don't have a full feature around this. But if you do put your file into SPO/Group/ODB or any other place, you can add a clickable hyperlink to that file in the description of the video.

When you are editing the description of the video, just paste the hyperlink in there. When users view your video that link will be clickable.

Here's an example where I linked to the slides from a meeting we recorded...