It does work but it's an area of Vix that I believe causes a lot of confusion for users who have used Sky+ in the past.
This is how Sky+ works:
Let's say I am watching Sky1 from 8pm to 10pm. There are 2 programs on during that time, one from 8pm to 9pm (Matlock) and one from 9pm to 10pm (Murder She Wrote). At 9.15pm I hit pause to make a cuppa. At 9.20pm return to the TV and hit play. At 9.30pm I decide to record "Murder She Wrote" for my wife. So I hit record. At this point, all the timeshift buffer from 9pm to 9.30pm is automatically saved into "Recordings" and the rest of the program is automatically appended to the end of the "Murder She Wrote" recording file. If my wife was to join me at 9.45pm that same evening, it's possible to browse into "Recordings" and watch "Murder She Wrote" that started at 9pm from the beginning (even though it hasn't finished yet). The last 15 minutes of the program of is recorded as normal. With Sky+ in this scenario, it wouldn't be possible to record Matlock.
This is how Vix works:
Take the same scenario again. Let's say I am watching Sky1 from 8pm to 10pm. There are 2 programs on during that time, one from 8pm to 9pm (Matlock) and one from 9pm to 10pm (Murder She Wrote). At 9.15pm I hit pause to make a cuppa. At 9.20pm return to the TV and hit play. At 9.30pm I decide to record "Murder She Wrote" for my wife. So I hit record (there is more than 1 way to record with Vix, so depending on how you record, your experience may vary). Now this is where Sky+ and Vix differ. The User Experience with Vix is not as "clean" as the Sky+ IMHO but the level of control makes up for this. After hitting record, I get presented with something like 6 or 7 options about what I want to record (I'm not in front of my TV so I don't have the exact list). Again, IMHO this is very confusing the first time you see this list!!! There is one option to save the current event and timeshift. This is normally what I want to do and is most similar to Sky+. If I take this option, the part of "Murder She Wrote" from 9pm to 9.20pm is still in the timeshift buffer - this will only get written to the recordings folder AFTER 10pm when the program is finished. So going back to the initial example, if my wife was to join me at 9.45pm that same evening, it's NOT possible to browse into "Recordings" and watch "Murder She Wrote". We'd have to wait until 10pm for "Murder She Wrote" to appear in recordings.
But there's more ... at 9.45pm if I hit record again and get shown the menu with 6 or 7 entries and I chose "Select Event", I can see it's also possible to record "Matlock". If I chose "Matlock", it immediately gets saved to disk and it's possible to watch in the "Recordings" immediately. This will work for several hours of timeshift on the same channel. This is where Vix is far superior to Sky+.