[Mike Clasby]

The easiest way is to add the effect Posterize Time and set the frame rate to half of the footage or comp frame rate. That’ll grab and hold every other frame.

[Mike Clasby]

Select the keyframes you want to rove proportionally, Alt-drag one end or the other.

[Mike Clasby]

You can replace the footage in the project window with, Right-Click>Replace Footage>File.

Or maybe better is to swap-out a layer in a Comp, by selecting the layer to be replaced, then Alt-Dragging new footage from the project window onto the selected layer (oh, yeah, that new footage needs to already be in the project window for this one).

[Mike Clasby]

If you want straight or flat ends on each end of the wave form, put the Audio Spectrum on masks, three masks to be exact, one in the middle for the waveform, one on each end of the waveform. Three instances of Audio Spectrum on the solid layer, each referencing a different mask, the middle have the audio file as the Audio Layer, the outside flatliners having Audio layer set to None.

You can simply duplicate the middle mask three times, then double click one and move it horizontally while holding the shift key to keep it perfectly horizontal. YOu can move vertices (the ends) in the same way.

Now this sounds like a bit of a pain, but it should just be a onetime setup, if you choose to make an animation preset.

Hit U on the keyboard, then select the three masks and the three instances of Audio Spectrum, then Save Animation Preset and name it accordingly.

Now in a new comp, Add the audio file, add a New Solid, select the solid, Animation>Recent Animation Preset>Choose the Audio Spectrum (or whatever you named it). Then in the middle Audio spectrum, choose the Audio File as the “Audio Layer”. Done. Faster than it sounds.

[Mike Clasby]

In case the footage has a little camera shake in it (don’t they always?), this tut will show you how to track the footage so you can have your replacement piece to match the video movement.

https://library.creativecow.net/articles/kramer_andrew/Set_Extensions.php

You can make the replacement in photoshop, either cloning out the chair with dresser wood, or replace it with something all together.

[Mike Clasby]

Do these help?

Keep motion in perspective

https://studio.adobe.com/us/tips/tip.jsp?p=1&id=100241&xml=aft65cornerpin

Using the new Motion Tracker

https://studio.adobe.com/us/tips/tip.jsp?p=1&id=487&xml=aft6ttmotiontracker

[Mike Clasby]

Here’s a good place to start:

https://www.motionscript.com/mastering-expressions/random-3.html

Go to “Let There Be Light”, a nice flicker with control over the ranges of randomness.

Ask if you have inplemnentation problems.

[Mike Clasby]

Convincing Fire is not easy to do. If you can’t find some live footage to composite, Trapcode has a plugin, Form, that is the closest I know.

https://www.trapcode.com/products_form.html

THIS IS NOT A PLUG. I don’t even own one trapcode product. Sad but true.

[Mike Clasby]

As to your first question, Hmmm… you probably can with CS3, see this page:

https://www.motionscript.com/design-guide/obscuration.html

If you subbed in one of your fog layers for the Lens Flare, having the expression adjust the opacity instead of Flare amount, it should work. I don’t have CS3 so can’t test it.

[Mike Clasby]

For the speed change you can Time Stretch or Time Remap the clip, but a five fold spread will leave it very star-stepy, so you need time Warp, AE7 or better, see this tut for details:

https://www.videocopilot.net/tutorials.html?id=30