Two options (for now) depending on what you actually have: …

Two options (for now) depending on what you actually have:
If it's real audio saved as .mp4/.m4a (no video) → great, I'll add it as-is.
If they're actual .mp4 video clips → better to convert them to MP3 320 kbps (or .m4a). It's a quick export and sounds just as good, without dragging the video along.