can I import avi files into indesign?

The thing is apart from that, many desktops nowadays don't have Flash installed,  you can't control which Acrobat reader the enduser may use to read the PDF

the .pdf format does play videos. HOWEVER....... those videos will only work/play on desktop devices. no mobile devices. and they may not work correctly sometimes for some users.

You can of course do it

https://helpx.adobe.com/ie/indesign/using/movies-sounds.html

However, I think Derek's solution is better.

You can Place video files into indesign but they won’t play as PDFs - instead use InDesign’s Publish Online, FXL ePub or in5 Digital Magazines, Mobile Apps, Web Banner, Microsites, & more from InDesign with in5 - Home

Discussion moved from Enterprise & Teams to InDesign​ where you can find answers from InDesign experts.

The short answer seems to be yes. Take a look at: Add movie and sound files to InDesign documents