And here we go, version 0.9 Beta... http://www.redbubble.com/people/horemweb/works/20751261-dw-in-hoffi-coffi
(Man, it is 1:30AM and I have to get up early... But when an idea stucks, sleeping time sucks... :D :D :D )
Thank you, Hatakend! Have a lingot in return... :D
Did you everybody realize that this is also available as a travel mug? (And many other things, but they have less sense...) http://www.redbubble.com/people/horemweb/works/20751261-dw-in-hoffi-coffi?p=travel-mug
For those who may be interested, I celebrated yesterday night's soccer results (Cymru vs. Belgium 3 - 1) with a small mutation of the "dw i'n hoffi coffi' mug and gift design. You may want to check it on RedBubble http://www.redbubble.com/people/horemweb/works/22341804-dw-in-caru-p-l-droed or on DeviantART :) Dw i'n caru pel-droed :D
Like is a Stative verb.. meaning it relates to a state. "I like something" means that I always like it. But it CAN be used as a progressive verb, meaning it has action. I may not like coffee and lemon most of the time, but if at this moment I am, then "I am liking coffee and lemon" is a progressive verb. It may not be the most common usage, but it's not incorrect. However, I concede that for the purpose of this course, it may not be recognized, and that's okay. I was just wondering.
You almost always use yn without exception, but eisiau (want) is the exception! Eisiau was originally a noun, not a verbnoun, but now it is used just like a normal verbnoun except for the fact that you don't use yn before it.
The only other exceptions I can think of off the top of my head are angen (need - that was a noun too) and moyn (want - where the yn is optional).
Not a native, but...
My understanding is that it's an uninflected form of the verb. It's parallel to the present participle in English in that it is often paired with a form of the existence verb ("to be" in English, bod yn Gymraeg) to express an ongoing occurrence, and it doesn't conjugate with respect to the subject, because that's the job of the "be"/bod verb.
Also parallel to English is its prominence in spoken language over the simple inflected form of the verb. Think about when you talk with other people: it's rare that you say aloud "I eat; he drinks; she walks." Typically, you talk about things in the present progressive: if asked about goings-on, you'll tend to say "I'm eating; he's drinking; she's walking." And so it is with Welsh: instead of fussing with conjugating the verb stem (which can be unpredictable), you just start with a form of bod, insert the subject, then yn+verbnoun (the "infinitive").
While it's not an exact gloss, I try to "think Welsh" by imagining the sentence as "Be (the subject) in the doing (of something)." So: I'm drinking coffee→Be I in the drinking of coffee→Dw i'n yfed coffi.
I think the course creators were more focused on creating a crash course for spoken Welsh; you can find a more thorough explanation of Welsh verbs (including literary forms) here.
Sorry. A verbnoun is a Celtic thing, as it has both verb and noun properties. But you can think of it as an "infinitive" if you want or the basic form you find in a dictionary, so hoffi meaning "like, to like, liking" is the verbnoun, likewise canu "sing, to sing, singing", mynd "go, to go, going", siarad "speak, to speak, speaking" and so on.