Why 300MB? Why MKV? And is this trend a blessing for data-conscious users or a legal minefield?
A: No. While a VPN hides your IP from your ISP, it does not hide the files on your hard drive from a court order. Furthermore, most free VPNs log your data and sell it to advertisers. Final Note to the Reader:
A: iPhones do not natively support MKV's DTS or AC3 audio codecs. You need VLC for Mobile or Infuse.