Hear, hear. I'm getting kinda desperate in my non existing pursuit of being able to focus / getting things done. I am considering meditation but I'm not sure there's actual evidence that it actually makes it easier to focus.
Meditation consists of two main "directions": Concentration practice and contemplation practices. Most schools of meditation has one of these as their main focus, but contemplation practice includes certain levels of concentration practice as pre-requisite, either explicitly (separate ways to train your concentration), or indirectly as part of practising a form of contemplative meditation.
Concentration practice is generally what you might think of if you think of meditation as emptying your mind, repeating mantras or similar.
Try this simple exercise:
Set an alarm for five minutes.
Sit comfortably. Floor is traditional, but not at all necessary; a position that is comfortable enough that physical discomfort does not distract you too much is much more important. Half close your eyes (you can meditate with your eyes fully open, or fully closed, or anything in between - it is a matter of preference, but until you know consider that fully open means your eyes will be dry and there will be more distraction, and fully closed increases your chance of falling asleep).
Then breathe in and out through your nostrils. Count 1, 2, 1, 2, 1,2 as you breathe in and out.
Every time you notice that you have stopped counting, try to estimate (quickly) how long you have been "off track", and start again, until the alarm goes off.
Congratulations, you have just meditated. If you can make the whole five minutes, try it again but without counting, just noticing the breath.
Most first timers/beginners are lucky if they manage 30 seconds consecutively without going off track, often for minutes at a time. If you manage the full five minutes without finding yourself thinking about something completely difference, your concentration skills are already well above average. With practice, you can keep attention like that for hours. And it does translate to being able to keep focus in other situations.
If you want to try more, "Mindfulness in Plain English" is a good introduction: http://www.urbandharma.org/udharma4/mpe.html ; the html version is free. Gil Fronsdals "Introduction to Meditation" series of recordings are also great, free, and includes guided meditations that are quite useful to beginners: http://www.audiodharma.org/series/1/talk/1762/
These focus on vipassana - insight meditation or mindfulness. This is a contemplation practice, but the introductions above spend a substantial part on the basic concentration practice of meditating on the breath, which is a common concentration practice in many schools of meditation.
The "mindfulness" part is sort of in the gaps: Rather than trying to hold an "iron grip" on your mind to focus on the breath, the purpose is closer to "catching you thinking" (or feeling, or sensing, etc.) and paying attention to the sensations an quality of what arises in you, while you try not to get pulled away from paying attention to the breath, and then rather than forcing the thought away, to let it "fade" by "simply" (it is by no means simple) not follow the thought with another.
Both of these introductions are of buddhist origins, though if it matters to you one of the things that appealed greatly to me about them is that they are careful to keep the material mostly secular (there's some brief mentions of buddhist faith, but they are explanatory rather than essential toe the meditation practice).
When I started meditation I thought it would give me some sort of mental superpowers (Tibetan Buddhist IMO are quick to sell you on those). However in my experience the benefit is more like developing resilience against all the drama and bullshit that life or your own mind throws at you. A potential downside is that I notice more clearly how other around me are swept up into unnecessary frustration or anger. Of course it would be overstating to say I'm a competent meditator, but on some days I consider meditation the most valuable thing I do for myself.
I'm motivated now to try the guided meditation your linked above. Thanks!
Spoiler alert - you're supposed to discover by direct experience that your real self is neither a homunculus looking out through your eyes, nor is it coterminous with your body, and this direct experience that your true self is everything that is, is intended to lead to compassion for other beings.
(Although I also attacked the lack of attention span problem by doing totally seeminly dumb tasks such as reading a book backwards which makes no sense and really forces you to re-focus all the time. From a few minutes I was able to get up to 10, and later 15 minutes per time without huge mental wandering. Same goes for meditation, from minutes to tens of minutes with ease in a matter of weeks.)
http://www.samharris.org/blog/item/mindfulness-meditation
Here is a bit more background on it: http://www.samharris.org/blog/item/how-to-meditate
There is plenty of scientifically backed studies and documents out there when it comes to mindfulness If you are a skeptic though, as am I, be wary of the masses of esoterically/religiously contaminated resources on the web, when it comes to meditation.