Popup about missing .resource file appears when refreshing Asset Database after saving new MP4/WebM file

Reproductions steps:
1. Open the attached "case_1305732.zip" project
2. Load SampleScene
3. Enter Play mode

Expected result: no popup window appears
Actual result: a popup with an error message about a .resource file that cannot be found appears

Reproduced with: 2020.1.0a15, 2020.1.17f1, 2020.2.7f1, 2021.1.0b10, 2021.2.0a7
Not reproducible with: 2018.4.32f1, 2019.4.21f1, 2020.1.0a14

Note: the popup error message: "Opening file failed: Opening file C:/Users/edvardas.nov/Downloads/case_1305732/Library/TempArtifacts/Primary/f3bb3938c36f349499ad2f5a40d212c4.resource: The system cannot find the file specified."