for both of those, you just choose one of the included presets. including QuickTime Animation with an alpha channel and WebM with an alpha channel. you could use it to convert videos to lots of different formats. This app seems quite useful even if you have some other video editing app.

Translated to Spanish, French, Czech, and German.

Eye dropper tool to pick neutral color for white balancing.

3-way (shadows, mids, highlights) color wheels for color correction and grading.

Video filters: blur, color grading, crop, glow, mirror, saturation, sharpen.

Multi-core parallel image processing when not using GPU (and frame-dropping is disabled).

Edit Melted playlists including suport for undo/redo.

Control the transport playback of Melted units.

Connect to Melted servers over MVCP TCP protocol.

Unlimited undo and redo for playlist edits including a history view.

Create, play, edit, save, load, encode, and stream MLT XML playlists.

Stream (encode to IP) files and any capture source.

Capture (record) SDI, HDMI, webcam (V4L2), JACK, PulseAudio, IP streams, X11 screen.

Encode/transcode to a variety of formats and codecs thanks to FFmpeg (or libav as-built).

Load and play complex MLT XML file as a clip.

Save and load trimmed clip as MLT XML file.

Blackmagic Design SDI and HDMI for input and preview monitoring.

Frei0r video generator plugins (e.g., color bars and plasma).

Network stream playback (HTTP, HLS, RTMP, RTSP, MMS, UDP).

Multi-format timeline: mix and match resolutions and frame rates within a project.

Frame-accurate seeking for many formats.

Supports many image formats such as BMP, GIF, JPEG, PNG, SVG, TGA, TIFF, as well as image sequences.

Supports oodles of audio and video formats and codecs thanks to FFmpeg (or libav as-built).

Shotcut is a free, open-source, cross-platform video editor.

Shotcut install