I was recently given a keynote presentation which contained a movie. When I played the presentation the sound worked but the movie was blank. It turned out the movie was not in a format that Quicktime could play. There are many such formats. When I tried to play the movie in Quicktime I got an error saying ‘The document could not be opened. The movie is not in a format that QuickTime Player understands.You may need to install additional software to open this type of file.’Â
Here’s what to do.
To apply this change to all files of this type, click the 'Change All' button. For optical media, like CDs or DVDs, go to Apple - System Preferences and choose 'CDs/DVDs' in the Hardware section. Choose 'Other Application' from the respective popup menu button. The list is alphabetical, so VLC should be near the bottom of the list.
Free App To Play Videos
To play movies in Keynote, iMovie etc:
Perian is a handy free program that allows your mac to play almost any movie format, including AVI files from a Windows computer. Perian just sits in the background and allows other programs (like Keynote) to play movies that they wouldn’t normally be able to play. Â It claims to play all the following movie formats: AVI, DIVX, FLV, MKV, GVI, VP6, and VFW, MS-MPEG4 v1 & v2, DivX, 3ivx, H.264, Sorenson H.263, FLV/Sorenson Spark, FSV1, VP6, H263i, VP3, HuffYUV, FFVHuff, MPEG1 & MPEG2 Video, Fraps, Snow, NuppelVideo, Techsmith Screen Capture and DosBox Capture.
You can download it for free from perian.org. To install it simply click on the icon and it will install itself as a Preference Pane. It sits in the background – you don’t need to do anything. Your normal programs such as Keynote and Quicktime will now be able to play any movie format. You will need to quit and restart Quicktime or Keynote after you install Perian.
To watch movies in your screen in a player.
Perian won’t play every movie.  Perian won’t play wmf files and some kinds of AVI movies. To play all files try out VLC for Mac OS X.  VLC is awesome and allows you to watch any movie. The only problem with VLC is that it only allows you to watch the movie in it’s own player, not in Keynote or other programs.
QuickTime Player User Guide
QuickTime Player has onscreen playback controls that let you play, pause, fast-forward, or rewind your video or audio file.
You can also use playback controls to share a file, or play a file on an AirPlay-enabled device.
Open a file
To open a video or audio file in the QuickTime Player app on your Mac, do any of the following:
Double-click the file in the Finder.
If your videos or audio files are in iCloud Drive, click iCloud Drive in the Finder sidebar, then double-click your file. See Use iCloud Drive to store documents on your Mac, iPhone, and iPad.
Choose File > Open File, then select a file, and click Open.
If a file is an older or third-party media format, QuickTime Player may convert it before playing.
Tip: You can also open a file you’ve worked with recently by choosing File > Open Recent.
Play Video Files Pc
Play a file
In the QuickTime Player app on your Mac, open a video or audio file.
Move the pointer anywhere over the movie to show the playback controls. Controls for audio files are always visible.
Tip: Depending on the duration of the file or how much time is left during playback, you can change the playback or reverse playback speed by 2x, 5x, 10x, 30x, or 60x. Simply keep clicking the forward or rewind button until you play at the desired speed.
Note: Some media files display timecode—an 8-digit code (00-00-00-00)—in the playback controls, instead of the 4-digit code showing the remaining time. The timecode shows source time information about a specific frame or recorded point, like the time of the original recording, or the frame number. When editing a project, you can use the timecode to navigate to an exact location of a frame in the media file.
Use the playback controls to play the video or audio file; you can drag the controls to move them out of the way.
If your Mac has a Touch Bar, you can use the playback controls in the Touch Bar.
If you want the file you’re playing to appear in front of all other windows on your screen, choose View > Float on Top so a checkmark appears next to it. Choose it again to turn it off.
Play a video with picture-in-picture
With picture-in-picture , you can play a video in a resizable floating window, so you can see it on your screen, while you do other tasks on your computer.
Play Wmv File On Mac
In the QuickTime Player app on your Mac, open a video file.
Use the playback controls to play the video file.
Click the picture-in-picture button in the playback controls.
You can click and drag the picture-in-picture window to anywhere on the screen, or click and drag any edge of the window to resize it.
Click the full screen button or the close button to close the picture-in-picture window.
Play a file in a continuous loop
Which Mac App Plays All Video Files 2017
You can set a video or audio file to play continuously, so that it plays to the end and then starts over from the beginning.
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Select the video or audio file you want to loop.
Choose View > Loop so a checkmark appears next to it.
To turn off continuous play, choose the command again; the checkmark is removed.
You can also use keyboard shortcuts or gestures to open, play, or pause a file, and more.