The flute part is played by Shri Pandit Hariprasad Chaurasia for the film: Geet 1970
From the title cards you can make out here at 0:03:29


It is very difficult to get wav or flac on the net now. Most of the old songs have already been
Converted to mp3 or some other format to save space/storage. Even cassette/magnetic tapes are not available now in the market.
Probably All India Radio, Mumbai or New Delhi may be having original LP/Vinyl records (doubtful).
Now again music enthusiasts are demanding for LPs/vinyl records.

May be available with stores like this:
http://www.mid-day.com/articles/band...overs/15848158
http://www.polkacafe.com/places-to-f...ndia-1153.html
Any of our members residing at Mumbai/New Delhi may help you in this regard.