Sign in to web.airdroid.com, find the Videos icon and click it.
How to download videos?
Select one or more videos you want to download and click Download on the upper right corner, the video will be downloaded from the Android device to the computer (saved in a zipped file if you select more than one video).
How to upload videos?
Click Upload on the upper right corner, and then drag and drop videos or folders to the box to upload.
How to delete videos?
Choose one or more videos you want to delete and click the Trash icon, then click OK.
How to search videos?
You can enter a keyword in the upper left corner of Videos to search.
Manage files in extSD via AirDroid Web is not supported on Android 4.4+ as Google has restricted the access permission to it.
However, Android 5.0 restored the functionality of SD card. With AirDroid v3.1.5, you can manage files in external SD card with AirDroid Web again!
More info: [Help & FAQ] How to Manage Files Saved to External SD Card on Android 5.0+?