Craig oratedPick your audience
One of the great things about web video is how contextual it can be. Using search terms and tag clouds for video can be very effective at getting the people that you want, to watch your video. Try not to deviate from the focus that you have highlighted because the average internet user knows when they are being drawn off the subject.
Be interesting / entertaining
No one likes to be blasted with marketing and sales banter even if the media’s aim is to sell a product. The success of podcasting is a testament to this, people enjoy being engaged by their media. If you really want to sell something thorough video online either an entertaining fresh concept should be worked on (as in viral videos) or gift large quantities of useful information about a subject in return for a small amount product reference / placement / promotion
Be concise
On the internet it’s way easier to change the channel! People know when they are being waffled at. Keep your content clear and to the point.
Use (but dont over use) effects
Effects and motion graphics can indeed add that element of professionalism to video and due to the increasing amount of talent available there it is getting cheaper to have the razamataz of Hollywood on your web video. These effects should only be used where appropriate such to compliment & enhance the content of the video.
Get a good presenter
Another crucial factor! You have informative information to impart you must realise the audience and get a presenter that will fit with the content. You wouldnt want a BBC voice for a punk documentary! If you are doing corporate production you may find the CEO wanting his 10 seconds of fame. This is fine as long as they are well directed and (unless they have the charisma) it is limited to that 10 seconds!
Remember your size
Unlike traditional broadcast standards, using video on the net is a lot more restrictive with regard to size. You can use some crazy resolutions (i have designed in 900×100!) and this can release some new creativity with it, allowing you to play with completely new composition sizes and aspects.
Remember the web developer who will have to sit the video, make sure that there is a good dialogue of communication between the video producer and the person who will be positioning it on the site. If the video is going to be reduced in resolution for web mounting, have an appreciation for this for the elements in the video, that fancy bit of complimentary animation that looks great on that 20″ screen of yours might be barely visible on the final seated web video!
A note on current compression
Compression tools for the net are continuously being updated and ever since the invention of the H.264 codec ( WIKI article ) it has been getting easier to use lower bit rates for very high qualities. I wont go into the details of the plus’ and minus’ of different codecs but I will say that now flash video have added support for the h.264 codec, it looks like it will be around and kicking for a few years yet.
Signing off