When sharing a video that's saved in Google Drive, don't use Add File/Link/External Tool. Instead, use Add Page and embed the video.
Follow these instructions to share videos from online sources such as Google Drive, YouTube and others with your students in the smoothest way way possible on Schoology.
Special thanks to Sandy Smith for helping us identify and address this issue!
The Better Way - Adding a Page and Embedding the Video
Click the add content icon, then Image/Media
Switch tabs to your video in Google Drive.
Click the three dots in the top right, then Embed item..
Be sure your video is shared as "Anyone with the link can view" to avoid issues!
Select and copy all the embed code. Be sure to select it all!
Paste the embed code into the Link/Embed field.
Give your page a title. Optionally, add any other text or media to your page, then click Create.
Congrats! You now have given your students the easiest way possible to watch your video on Google Drive!