1) Some software companies include a demo walk-through of their product on their sales pages. The reasoning is this helps visitors see exactly what they will be getting. This adds transparency and boosts trust. Both of these help conversion rates. Plus, there's power in "show, don't tell".
2) Some software companies do *not* include a demo walk-through of their product on their sales pages. The reasoning is many people will get overwhelmed. Plus, the demo video reminds people they'll still have to actually do something with the software. Since many people are lazy, this may backfire and hurt conversions. Sell the sizzle, not the stake, and all that.
3) Some software companies just show screenshots of the main (not all) functions, and explain how those specific functions will solve specific problems or give benefits to customers. I have also seen some websites show animated gifs of functions.
What do you think is the best approach, and why?