Problem to recognize mp4 and mp3 files.

Hi, I'm trying to use a video and a sound in my Android app.
ItelliJ IDEA doesn't recognize the mp4 and the mp3 files. (It put a question mark on them).
In the code, I write:
String videoPath= "android.resource://mobile2017.ifrensh/"+R.raw.alphabet_song;

but I get this error:
Error:(33, 73) error: cannot find symbol variable alphabet_song

Help me please.

/*In works like a charm for the image*/
Thanks.