use ffmpeg.... the highest resolution is 704x516 ....
Code:
ffmpeg -i "http://c.brightcove.com/services/mobile/streaming/index/rendition.m3u8?assetId=3826852718001&pubId=3692957913001&videoId=3826648527001" -vcodec copy -acodec copy -absf aac_adtstoasc out.mp4
