avformat/movenc: fix mime-types in movenc.c

https://developer.apple.com/library/ios/documentation/AppleApplications/Reference/SafariWebContent/CreatingContentforSafarioniPhone/CreatingContentforSafarioniPhone.html

says video/mp4

suggested by BBB on irc.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/movenc.c

@@ -5594,7 +5594,7 @@ MOV_CLASS(mp4)
 AVOutputFormat ff_mp4_muxer = {
     .name              = "mp4",
     .long_name         = NULL_IF_CONFIG_SMALL("MP4 (MPEG-4 Part 14)"),
-    .mime_type         = "application/mp4",
+    .mime_type         = "video/mp4",
     .extensions        = "mp4",
     .priv_data_size    = sizeof(MOVMuxContext),
     .audio_codec       = AV_CODEC_ID_AAC,
@@ -5648,7 +5648,7 @@ MOV_CLASS(ipod)
 AVOutputFormat ff_ipod_muxer = {
     .name              = "ipod",
     .long_name         = NULL_IF_CONFIG_SMALL("iPod H.264 MP4 (MPEG-4 Part 14)"),
-    .mime_type         = "application/mp4",
+    .mime_type         = "video/mp4",
     .extensions        = "m4v,m4a",
     .priv_data_size    = sizeof(MOVMuxContext),
     .audio_codec       = AV_CODEC_ID_AAC,
@@ -5666,7 +5666,7 @@ MOV_CLASS(ismv)
 AVOutputFormat ff_ismv_muxer = {
     .name              = "ismv",
     .long_name         = NULL_IF_CONFIG_SMALL("ISMV/ISMA (Smooth Streaming)"),
-    .mime_type         = "application/mp4",
+    .mime_type         = "video/mp4",
     .extensions        = "ismv,isma",
     .priv_data_size    = sizeof(MOVMuxContext),
     .audio_codec       = AV_CODEC_ID_AAC,