How to reproduce:
1. Install Unity Accelerator on a machine that can be reached from both Linux and Windows
2. Open the user attached project (VideoCS.zip)
3. Make the Editor use the Unity Accelerator by setting the default mode to enabled and providing an IP address in "Edit>Preferences...>Editor>Cache Server (global)"
4. Reimport the "file_example_MP4_1920_18MG.mp4" video located in the "MP4Sample" folder
5. Close the project and delete its "Library" folder
6. Open the project on Windows
7. Make sure the project is set up to pull the video from the Unity Accelerator by ensuring the IP is still set, and closing and reopening the project if necessary

Expected result: the failed video import isn't uploaded to the unity Accelerator or isn't pulled from it, making the video file usable
Actual result: the failed video import is uploaded to and pulled from the unity Accelerator, resulting in an unusable video file

Reproducible with: 2019.4.15f1, 2020.1.14f1, 2020.2.0b13, 2021.1.0a6
Could not test with: 2018.4.29f1 (Connection failed to Unity Accelerator)

Notes:
1. Tested on Ubuntu 18.04 and Windows 10
2. Used Unity Accelerator version 1.0.628+gea3998c
3. Reimporting the video resolves the issue