Storyline 360 now supports WebM video files, giving you more flexibility when adding media to your courses. Keep reading to learn more.

• Add WebM Videos
• About the Published Output
• Understand Alpha-Channel Transparency in WebM Videos
• Make Your Videos Accessible
• Understand Compatibility

Add WebM Videos

You can now add a WebM video directly to your project. Use any of the following methods:

• Drag the video file from your computer and drop it on your course slide.
• In Slide View, go to the Insert tab on the ribbon, click the Video drop-down arrow, and choose Video from File. 
• In Form View, go to the Home tab on the ribbon, click the Media drop-down arrow, and choose Video from File.

About the Published Output

Depending on your selected video quality setting, Storyline 360 publishes your video as either an MP4 or a WebM file:

Adaptive video quality

• This option uses HTTP Live Streaming (HLS), which doesn’t support WebM. All videos are published as MP4s, even if you added a WebM file.

Static video quality

• This option preserves the original format. MP4 files stay MP4, and WebM files stay WebM.

Understand Alpha-Channel Transparency in WebM Videos

Storyline 360 supports alpha-channel transparency—the ability to layer a video over slide content for a seamless look—in WebM videos on many desktop browsers, including Microsoft Edge, Google Chrome, and Firefox. On browsers that don't support transparency—like Safari and most mobile browsers—Storyline 360 displays the video's background color instead.

Make Your Videos Accessible

Providing accessible videos improves inclusivity, helping all learners understand the content better. For tips on creating accessible video content, start with this resource. Then, consider the following design tips:

• Ensure contrast and visibility. When using transparent or layered video elements, select background colors with sufficient contrast (at least 4.5:1) to ensure that captions, controls, and visuals are legible. (1.4.3 Contrast Minimum)
• Keep it simple. If your video includes layered animations or interactive elements, give learners the ability to pause, stop, or reduce motion. Keep visual effects purposeful, synchronized with narration or on-screen text, and aligned with learning goals to minimize cognitive load. (2.2.2 Pause, Stop, Hide)
• Test in various environments. Because visual effects and transparency can vary, test your course on multiple browsers and devices to ensure that your content is accessible across all environments.

Understand Compatibility

WebM support is exclusive to Storyline 360 as of the December 2, 2025 update. If you add a WebM video to your project, that file won't open in earlier versions of Storyline 360. To restore compatibility, remove the WebM video.