EMVideoMessageBody 成员列表

成员的完整列表，这些成员属于 EMVideoMessageBody,包括所有继承而来的类成员

	displayName	EMFileMessageBody
	downloadStatus	EMFileMessageBody
	duration	EMVideoMessageBody
	fileLength	EMFileMessageBody
-	initWithData:displayName:	EMFileMessageBody
-	initWithLocalPath:displayName:	EMFileMessageBody
	localPath	EMFileMessageBody
	remotePath	EMFileMessageBody
	secretKey	EMFileMessageBody
	thumbnailDownloadStatus	EMVideoMessageBody
	thumbnailLocalPath	EMVideoMessageBody
	thumbnailRemotePath	EMVideoMessageBody
	thumbnailSecretKey	EMVideoMessageBody
	thumbnailSize	EMVideoMessageBody
	type	EMMessageBody