[YifengMao]

Summary

• Resolve MediaWebPart configuration before selecting a mapping, including source-page context and VideoSet encoding/embed precedence.
• Map validated HTTPS iframe content to the public Embed component without trusted cached markup. Keep native HTML Field Security and framing checks in effect.
• Run asset handling and strict file lookup only in the selected File and Media branch; preserve the actual owning site, web, list, file IDs and URLs for same-site and cross-site conversion.
• Warn and skip missing, unsupported or placeholder media rather than emitting an empty file component. Leave shared DocumentEmbedLookup behavior and the global function pipeline unchanged.
• Keep the mapping entry points short in BuiltIn.cs, with media implementation in MediaWebPartMapping.cs and shared encoding/URL helpers in FunctionsBase. Update only the Media sections in both mapping XML copies.

Validation

• 47 focused tests passed (15 Media cases plus 32 existing regressions): mapping selection/order, safe encoding, VideoSet/context resolution, invalid inputs, transferred/retained file identities, and existing DocumentEmbed/slideshow/Page Viewer regressions.
• dotnet build .\src\lib\PnP.Framework\PnP.Framework.csproj -f net8.0 --no-restore passed.
• Ran public ConvertTo-PnPPage with explicit mapping/connection and isolated, hash-verified rebuilt Framework binaries. Read back saved controls and compared their identities to the actual files.
• Playwright confirmed real Embed playback and same-site/cross-site MP4 playback through completion, with no media-element errors.
• All run-owned tenant fixtures were removed; cleanup queries confirmed zero remaining test artifacts.

Scope and limitations

• Uses only the existing public Embed and File and Media components.
• Classic autoplay, loop, preview images and rendition switching are not preserved. VideoSet rendition-item URLs and rendition-only fallback are not added.
• Existing asset-transfer support is unchanged. If a valid file remains at its source, its source URL and identities are retained with an explicit access warning.
• Destination Embed policy is checked by the native component at render time; cached markup does not bypass it.

[YifengMao]

Playback screenshots

Player-only crops from the browser verification; tenant/account details are excluded and fixture filenames are redacted. These were captured before the behavior-preserving helper extraction. Playback was rechecked successfully on the final PR commit.

Embed

The migrated Embed component rendered the video, and Playwright confirmed playback time advancing without a media error.

Video frame: Big Buck Bunny, (c) copyright 2008, Blender Foundation / www.bigbuckbunny.org, CC BY 3.0. Screenshot cropped to the player.

File and Media: same-site conversion

The generated one-second MP4 played to completion. The native player shows Replay and 0:01 / 0:01.

File and Media: cross-site conversion

The copied destination MP4 also played to completion, with the destination file identities verified separately.

All run-owned test pages, videos, and copied asset folders were cleaned up after verification.