There were external video adapters that had various capabilities. The capabilities of them are based on the adapter, not on the SE. Although the SE does not have Color QuickDraw built-in, so the card would have to do something to bypass that. (For example, QuickTime will not run on an SE.)
For example, the RasterOps ColorVue SE supported 8-bit video.
For example, the RasterOps ColorVue SE supported 8-bit video.