Blender Video Editor

There are n channels: channel 0 is seen in top of other, channel with major number is seen in top of others.

Edit strip → Blend → Over Drop Edit strip → Image Offest → X,Y

Select strip and Add → Effect strip → Transform

Add proxy and timecode “Record Run” for every strip to have faster video preview.

Make strip overlapping in two channels. Select first strip, hold shift and select second. Then Add → Effect strip → gamma cross

• m: marker
• CTRL+m: rename marker
• HOME: adjust timeline
• k: cut (soft)
• b: box area selection
• SHIFT+b: box area zoom
• g: move selected objects
• h: mute strip. When transform a strip mute original.
• e: set end frame
• s: set start frame
• PAGEUP/PAGEDOWN: navigate in strip edge

* SHIFT+F2 to enter "video clip editor" mode 
* open video with top centered button
* adjust video setting as in the picture

optional: enable proxy mode clicking on “Build Proxy / Timecode”

optional: close video and reopen proxied version (in same folder as original in subfolder proxy)

move to desired frame and add mark on object

iterate with “Track markers” button (CTRL+T) and grab mark (G) on failed frames

select mask menu

add circle or square mask

drag on position (G) and parent with mask (CTRL+P)

add “Video Editing Workspace” with top “+” button

move to first frame and add movie clip

add adjustement layer

add mask in “Add strip modifier” in modifiers tab

select mask input type ande select Mask in Mask field

add effect strip → gaussian blur

select 20 in effect strip to blur masked area

adjust output video params and render with CTRL+F12