If you copy-and-paste (or drag-and-drop) artwork between Illustrator and Flash, the Paste dialog box appears, which provides import settings for the AI file being copied (or pasted).

Paste As Bitmap

Flattens the file being copied into a single bitmap object.

Paste Using AI File Importer Preferences

Imports the file using the AI file import setting specified in Flash Preferences (Edit > Preferences).

Apply Recommended Import Settings To Resolve Incompatibilities

Enabled by default when Paste Using AI File Importer Preferences is selected. Automatically fixes any incompatibilities detected in the AI file.

Maintain Layers

Enabled by default when Paste Using AI File Importer Preferences is selected. Specifies that layers in the AI file be converted to Flash layers (the same as if you selected Convert To Flash Layers from the AI Import dialog box). If deselected, all layers are flattened into a single layer.