Videos stored on an SD card can be imported with the Camera Connection Kit when formatted properly.
First, you must set up your SD card. In order for the iPad to recognize your media files, it has to think that the card you store your media on is from a camera.
To do this, set the folder structure to something of the type created on a card that's used in a camera, for example:
DCIM > 100DICAM >
Any media you want to be able to import to your iPad should be placed in the
100DICAM folder.
Now that your SD card is properly set up, you need to be sure your video files are recognized.
The first thing you must do is ensure that your files are H.264-compliant. You can use free encoding software like https://handbrake.fr/ , which has an iPad preset, to properly encode your files.
Once your files are compatible with your iPad, you must rename them. The name
must be eight digits with sequential numbers, just like when a camera takes
pictures, for example: DSC_0001, DSC_0002, and so on.