What you heard about most native speakers of Spanish pronouncing the letters "b" and "v" the same was is correct; however, what you understood about the pronunciation being like English "b" is not completely correct. How these letters are pronounced depends on their context; on the sounds that immediately precede and follow them. The same type of phenomenon also occurs with how most native speakers pronounce the letter "d" and with how they pronounce the letter "g" except when one of the letters "e" or "i" follows "g", although the details are a little different in each case. The letters "b" and "v" are pronounced like English "b" when (a) they are the very first sound after a pause, or (b) they follow one of the letters "m" or "n". In all other contexts most native speakers use a softer pronunciation for these two letters that resembles English "v" but is not identical to English "v". The most common way to pronounce "v" in English is to touch the lower lip against the upper teeth while the voice sounds. The most common way to pronounce the softer sound of "b" and "v" in Spanish is to gently allow the lower and upper lips to touch while the voice sounds, and in very relaxed speech some people touch their lips so gently that native speakers of English hear a "w" sound. For example, if you say either the word "beber" or the word "vivir" by itself, the first "b" or "v" usually has the hard pronunciation that resembles English "b", while the second "b" or "v" usually has the softer pronunciation with the upper and lower lips touching gently.